Organic compound, light-emitting element, light-emitting device, electronic device, and lighting device

ABSTRACT

A novel substance with which an increase in life and emission efficiency of a light-emitting element can be achieved is provided. A carbazole compound having a structure represented by General Formula (G1) is provided. Note that a substituent which makes the HOMO level and the LUMO level of a compound in which a bond of the substituent is substituted with hydrogen deep and shallow, respectively is used as each of substituents in General Formula (G1) (R 1 , R 2 , Ar 3 , and α 3 ). Further, a substituent which makes the band gap (Bg) and the T1 level of a compound in which a bond of the substituent is substituted with hydrogen wide and high is used as each of the substituents in General Formula (G1) (R 1 , R 2 , Ar 3 , and α 3 ).

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a carbazole compound and alight-emitting element using the carbazole compound. The presentinvention also relates to a light-emitting device, an electronic device,and a lighting device each including the light-emitting element.

2. Description of the Related Art

In recent years, research and development of light-emitting elementsusing electroluminescence (EL) have been actively conducted. In a basicstructure of such a light-emitting element, a layer containing alight-emitting substance is interposed between a pair of electrodes. Byvoltage application to this element, light emission can be obtained fromthe light-emitting substance.

Such a light-emitting element is of self-luminous type, and thus hasadvantages over a liquid crystal display in that visibility of pixels ishigh, backlight is not needed, and so on. Therefore, such alight-emitting element is probably suitable as a flat panel displayelement. Besides, such a light-emitting element has advantages in thatit can be manufactured to be thin and lightweight and has very fastresponse speed.

Further, since such a light-emitting element can be manufactured to havea film shape, surface light emission can be easily obtained. Therefore,a large-area element using the surface light emission can be formed.This is a feature that is difficult to obtain with point light sourcestypified by an incandescent lamp and an LED or linear light sourcestypified by a fluorescent lamp. Therefore, the light-emitting element isextremely effective for use as a surface light source applicable tolighting and the like.

Light-emitting elements utilizing electroluminescence are broadlyclassified according to whether they use an organic compound or aninorganic compound as a light-emitting substance. In the case where anorganic compound is used as a light-emitting substance, by applicationof voltage to a light-emitting element, electrons and holes are injectedinto a layer containing the light-emitting organic compound from a pairof electrodes, whereby current flows. Then, these carriers (i.e.,electrons and holes) are recombined, whereby the light-emitting organiccompound is excited. The light-emitting organic compound returns to theground state from the excited state, thereby emitting light. Note thatthe excited state of an organic compound can be a singlet excited stateor a triplet excited state, and light emission from the singlet excitedstate is referred to as fluorescence, and light emission from thetriplet excited state is referred to as phosphorescence.

There are many problems which depend on a substance in improving elementcharacteristics of such a light-emitting element. In order to solve theproblems, improvement in an element structure, development of asubstance, and the like have been conducted. For example, PatentDocument 1 discloses a light-emitting element in which a compound havingan anthracene skeleton and a carbazole skeleton is used as alight-emitting material. However, it cannot be said that thelight-emitting element has sufficiently high reliability.

Further, Patent Document 2 discloses a light-emitting element in which acompound which has an anthracene skeleton including a substituted orunsubstituted phenyl group and a carbazole skeleton and has an excellentcarrier-transport property is used. The light-emitting element has lowdrive voltage and has high reliability.

REFERENCE

-   [Patent Document 1] PCT International Publication No. WO 2005/113531-   [Patent Document 2] Japanese Published Patent Application No.    2009-167175

SUMMARY OF THE INVENTION

In the case where the compound described in Patent Document 2 is used inan element including a phosphorescent substance, the excitation energyof the phosphorescent substance might be quenched due to an insufficientT1 level (triplet excitation energy) of the anthracene skeleton in thecompound, which might make it difficult to obtain high emissionefficiency. In addition, in the case where the compound is used in anelement including a blue fluorescent substance, higher efficiency isdemanded though high emission efficiency can be obtained.

In view of the foregoing problems, an object of one embodiment of thepresent invention is to provide a novel substance with which thelifetime and emission efficiency of a light-emitting element can beincreased. Specifically, an object of one embodiment of the presentinvention is to provide a novel carbazole compound which can be used ina light-emitting element.

One embodiment of the present invention is a carbazole compoundrepresented by General Formula (G1).

Note that in General Formula (G1), R¹ represents any one of an alkylgroup having 1 to 12 carbon atoms, a substituted or unsubstituted phenylgroup, a substituted or unsubstituted biphenyl group, a substituted orunsubstituted naphthyl group, a substituted or unsubstituted phenanthrylgroup, a substituted or unsubstituted triphenylenyl group, and asubstituent represented by General Formula (G1-1). In General Formula(G1), R² represents any one of hydrogen, an alkyl group having 1 to 12carbon atoms, a substituted or unsubstituted phenyl group, a substitutedor unsubstituted biphenyl group, and a substituent represented byGeneral Formula (G1-2). In General Formula (G1), α³ represents either asubstituted or unsubstituted phenylene group or a substituted orunsubstituted biphenyldiyl group. In General Formula (G1), Ar³represents any one of a substituted or unsubstituted naphthyl group, asubstituted or unsubstituted phenanthryl group, and a substituted orunsubstituted triphenylenyl group.

Note that in General Formula (G1-1), Ar¹ represents any one of an alkylgroup having 1 to 12 carbon atoms, a substituted or unsubstituted phenylgroup, a substituted or unsubstituted biphenyl group, a substituted orunsubstituted naphthyl group, a substituted or unsubstituted phenanthrylgroup, and a substituted or unsubstituted triphenylenyl group. InGeneral Formula (G1-1), α¹ represents either a substituted orunsubstituted phenylene group or a substituted or unsubstitutedbiphenyldiyl group. In General Formula (G1-1), n represents 0 or 1.

Note that in General Formula (G 1-2), Ar² represents any one of an alkylgroup having 1 to 12 carbon atoms, a substituted or unsubstituted phenylgroup, a substituted or unsubstituted biphenyl group, a substituted orunsubstituted naphthyl group, a substituted or unsubstituted phenanthrylgroup, and a substituted or unsubstituted triphenylenyl group. InGeneral Formula (G1-2), α² represents either a substituted orunsubstituted phenylene group or a substituted or unsubstitutedbiphenyldiyl group.

Further, R¹ in General Formula (G1) may be any one of structuresrepresented by Structural Formulae (S-1) to (S-5) and General Formula(G1-1).

Note that in General Formula (G 1-1), Ar¹ represents any one of an alkylgroup having 1 to 12 carbon atoms, a substituted or unsubstituted phenylgroup, a substituted or unsubstituted biphenyl group, a substituted orunsubstituted naphthyl group, a substituted or unsubstituted phenanthrylgroup, and a substituted or unsubstituted triphenylenyl group. InGeneral Formula (G1-1), α¹ represents either a substituted orunsubstituted phenylene group or a substituted or unsubstitutedbiphenyldiyl group. In General Formula (G1-1), n represents 0 or 1.

Further, R² in General Formula (G1) may be any one of structuresrepresented by Structural Formulae (S-11) to (S-16) and General Formula(G1-2).

Note that in General Formula (G1-2), Ar² represents any one of an alkylgroup having 1 to 12 carbon atoms, a substituted or unsubstituted phenylgroup, a substituted or unsubstituted biphenyl group, a substituted orunsubstituted naphthyl group, a substituted or unsubstituted phenanthrylgroup, and a substituted or unsubstituted triphenylenyl group. InGeneral Formula (G1-2), α² represents either a substituted orunsubstituted phenylene group or a substituted or unsubstitutedbiphenyldiyl group.

Further, α³ in General Formula (G1), α¹ in General Formula (G1-1), andα² in General Formula (G1-2) may be separately any one of structuresrepresented by Structural Formulae (α-1) to (α-7).

Further, Ar¹ in General Formula (G1-1) and Ar² in General Formula (G1-2)may be separately any one of structures represented by StructuralFormulae (Ar-1) to (Ar-10).

Further, Ar³ in General Formula (G1) may be any one of structuresrepresented by Structural Formulae (Ar-11) to (Ar-15).

One embodiment of the present invention is a light-emitting elementusing the carbazole compound.

One embodiment of the present invention is a light-emitting deviceincluding the light-emitting element.

One embodiment of the present invention is a lighting device includingthe light-emitting device.

One embodiment of the present invention is an electronic deviceincluding the light-emitting device.

Note that the light-emitting device in this specification includes, inits category, an image display device and, a light-emitting device, anda light source. In addition, the light-emitting device includes, in itscategory, all of a module in which a connector such as a flexibleprinted circuit (FPC), a tape automated bonding (TAB) tape or a tapecarrier package (TCP) is connected to a panel, a module in which aprinted wiring board is provided on the tip of a TAB tape or a TCP, anda module in which an integrated circuit (IC) is directly mounted on alight-emitting element by a chip on glass (COG) method.

According to one embodiment of the present invention, a novel carbazolecompound can be provided. The carbazole compound has a wide band gap andis useful as a material of a light-emitting element. Further, thecarbazole compound has a high T1 level and is useful as a material of alight-emitting element. Further, the carbazole compound has a highcarrier-transport property and is useful as a material of alight-emitting element.

According to one embodiment of the present invention, a light-emittingelement that has high emission efficiency and long lifetime can beprovided. Moreover, according to one embodiment of the presentinvention, highly reliable light-emitting device, lighting device, andelectronic device in each of which the light-emitting element is usedcan be provided.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1A and 1B each illustrate a light-emitting element of oneembodiment of the present invention.

FIGS. 2A and 2B each illustrate a light-emitting element of oneembodiment of the present invention.

FIGS. 3A and 3B illustrate a light-emitting device of one embodiment ofthe present invention.

FIGS. 4A and 4B illustrate a light-emitting device of one embodiment ofthe present invention.

FIGS. 5A to 5E each illustrate an electronic device of one embodiment ofthe present invention.

FIG. 6 illustrates a lighting device according to one embodiment of thepresent invention.

FIGS. 7A and 7B are NMR charts of PCPN.

FIGS. 8A and 8B are NMR charts of3-(4-bromophenyl)-9-phenyl-9H-carbazole.

FIG. 9 is an MS chart of 3-(4-bromophenyl)-9-phenyl-9H-carbazole.

FIGS. 10A and 10B show an absorption spectrum and an emission spectrumof PCPN in a toluene solution of PCPN.

FIGS. 11A and 11B show an absorption spectrum and an emission spectrumof a thin film of PCPN.

FIGS. 12A and 12B are NMR charts of PCPPn.

FIGS. 13A and 13B show an absorption spectrum and an emission spectrumof PCPPn in a toluene solution of PCPPn.

FIGS. 14A and 14B show an absorption spectrum and an emission spectrumof a thin film of PCPPn.

FIGS. 15A and 15B are NMR charts of PCzPTp.

FIGS. 16A and 16B show an absorption spectrum and an emission spectrumof PCzPTp in a toluene solution of PCzPTp.

FIGS. 17A and 17B are NMR charts of mPCPPn.

FIGS. 18A and 18B show an absorption spectrum and an emission spectrumof mPCPPn in a toluene solution of mPCPPn.

FIGS. 19A and 19B show an absorption spectrum and an emission spectrumof a thin film of mPCPPn.

FIGS. 20A and 20B are NMR charts of mPCzPTp.

FIGS. 21A and 21B show an absorption spectrum and an emission spectrumof mPCzPTp in a toluene solution of mPCzPTp.

FIGS. 22A and 22B show an absorption spectrum and an emission spectrumof a thin film of mPCzPTp.

FIGS. 23A and 23B are NMR charts of NCPN.

FIGS. 24A and 24B show an absorption spectrum and an emission spectrumof NCPN in a toluene solution of NCPN.

FIGS. 25A and 25B show an absorption spectrum and an emission spectrumof a thin film of NCPN.

FIGS. 26A and 26B are NMR charts of NP2PC.

FIGS. 27A and 27B show an absorption spectrum and an emission spectrumof NP2PC in a toluene solution of NP2PC.

FIGS. 28A and 28B show an absorption spectrum and an emission spectrumof a thin film of NP2PC.

FIG. 29 illustrates a light-emitting element of Examples.

FIG. 30 shows emission spectra of light-emitting elements and acomparative light-emitting element of Example 9.

FIG. 31 shows voltage-luminance characteristics of the light-emittingelements and the comparative light-emitting element of Example 9.

FIG. 32 shows luminance-current efficiency characteristics of thelight-emitting elements and the comparative light-emitting element ofExample 9.

FIG. 33 shows luminance-power efficiency characteristics of thelight-emitting elements and the comparative light-emitting element ofExample 9.

FIG. 34 shows results of a reliability test conducted on thelight-emitting elements and the comparative light-emitting element ofExample 9.

FIG. 35 shows emission spectra of light-emitting elements and acomparative light-emitting element of Example 10.

FIG. 36 shows voltage-luminance characteristics of the light-emittingelements and the comparative light-emitting element of Example 10.

FIG. 37 shows luminance-current efficiency characteristics of thelight-emitting elements and the comparative light-emitting element ofExample 10.

FIG. 38 shows luminance-power efficiency characteristics of thelight-emitting elements and the comparative light-emitting element ofExample 10.

FIG. 39 shows results of a reliability test conducted on thelight-emitting elements and the comparative light-emitting element ofExample 10.

FIG. 40 shows emission spectra of a light-emitting element and acomparative light-emitting element of Example 11.

FIG. 41 shows voltage-luminance characteristics of the light-emittingelement and the comparative light-emitting element of Example 11.

FIG. 42 shows luminance-current efficiency characteristics of thelight-emitting element and the comparative light-emitting element ofExample 11.

FIG. 43 shows luminance-power efficiency characteristics of thelight-emitting element and the comparative light-emitting element ofExample 11.

FIG. 44 shows results of a reliability test conducted on thelight-emitting element and the comparative light-emitting element ofExample 11.

FIG. 45 shows emission spectra of a light-emitting element and acomparative light-emitting element of Example 12.

FIG. 46 shows voltage-luminance characteristics of the light-emittingelement and the comparative light-emitting element of Example 12.

FIG. 47 shows luminance-current efficiency characteristics of thelight-emitting element and the comparative light-emitting element ofExample 12.

FIG. 48 shows luminance-power efficiency characteristics of thelight-emitting element and the comparative light-emitting element ofExample 12.

FIG. 49 shows results of a reliability test conducted on thelight-emitting element and the comparative light-emitting element ofExample 12.

FIG. 50 shows emission spectra of a light-emitting element and acomparative light-emitting element of Example 13.

FIG. 51 shows voltage-luminance characteristics of the light-emittingelement and the comparative light-emitting element of Example 13.

FIG. 52 shows luminance-current efficiency characteristics of thelight-emitting element and the comparative light-emitting element ofExample 13.

FIG. 53 shows luminance-power efficiency characteristics of thelight-emitting element and the comparative light-emitting element ofExample 13.

FIG. 54 shows emission spectra of a light-emitting element and acomparative light-emitting element of Example 14.

FIG. 55 shows voltage-luminance characteristics of the light-emittingelement and the comparative light-emitting element of Example 14.

FIG. 56 shows luminance-current efficiency characteristics of thelight-emitting element and the comparative light-emitting element ofExample 14.

FIG. 57 shows luminance-power efficiency characteristics of thelight-emitting element and the comparative light-emitting element ofExample 14.

FIG. 58 shows results of a reliability test conducted on thelight-emitting element and the comparative light-emitting element ofExample 14.

FIG. 59 shows emission spectra of a light-emitting element and acomparative light-emitting element of Example 15.

FIG. 60 shows voltage-luminance characteristics of the light-emittingelement and the comparative light-emitting element of Example 15.

FIG. 61 shows luminance-current efficiency characteristics of thelight-emitting element and the comparative light-emitting element ofExample 15.

FIG. 62 shows a structure of a light-emitting element of Examples.

FIG. 63 shows emission spectra of a light-emitting element and acomparative light-emitting element of Example 16.

FIG. 64 shows voltage-luminance characteristics of the light-emittingelement and the comparative light-emitting element of Example 16.

FIG. 65 shows luminance-current efficiency characteristics of thelight-emitting element and the comparative light-emitting element ofExample 16.

FIG. 66 shows emission spectrum of a light-emitting element of Example17.

FIG. 67 shows voltage-luminance characteristic of the light-emittingelement of Example 17.

FIG. 68 shows luminance-current efficiency characteristic of thelight-emitting element of Example 17.

FIG. 69 shows emission spectra of light-emitting elements of Example 18.

FIG. 70 shows voltage-luminance characteristics of the light-emittingelements of Example 18.

FIG. 71 shows luminance-current efficiency characteristics of thelight-emitting elements of Example 18.

FIG. 72 shows luminance-power efficiency characteristics of thelight-emitting elements of Example 18.

FIG. 73 shows emission spectra of light-emitting elements of Example 19.

FIG. 74 shows voltage-luminance characteristics of the light-emittingelements of Example 19.

FIG. 75 shows luminance-current efficiency characteristics of thelight-emitting elements of Example 19.

FIG. 76 shows luminance-power efficiency characteristics of thelight-emitting elements of Example 19.

FIG. 77 shows results of a reliability test conducted on thelight-emitting elements of Example 19.

FIG. 78 shows emission spectra of light-emitting elements and acomparative light-emitting element of Example 20.

FIG. 79 shows voltage-luminance characteristics of the light-emittingelements and the comparative light-emitting element of Example 20.

FIG. 80 shows luminance-current efficiency characteristics of thelight-emitting elements and the comparative light-emitting element ofExample 20.

FIG. 81 shows luminance-power efficiency characteristics of thelight-emitting elements and the comparative light-emitting element ofExample 20.

FIGS. 82A and 82B are NMR charts of Cl-PPn2.

FIGS. 83A and 83B are NMR charts of Pn2BPPC.

FIGS. 84A and 84B show an absorption spectrum and an emission spectrumof Pn2BPPC in a toluene solution of Pn2BPPC.

FIGS. 85A and 85B show an absorption spectrum and an emission spectrumof a thin film of Pn2BPPC.

FIGS. 86A and 86B are NMR charts of PCPCl2.

FIGS. 87A and 87B are NMR charts of Pn2PPC.

FIGS. 88A and 88B show an absorption spectrum and an emission spectrumof Pn2PPC in a toluene solution of Pn2PPC.

FIGS. 89A and 89B show an absorption spectrum and an emission spectrumof a thin film of Pn2PPC.

DETAILED DESCRIPTION OF THE INVENTION

Hereinafter, embodiments and examples will be described in detail withreference to the drawings. Note that the present invention is notlimited to the description below, and it is easily understood by thoseskilled in the art that various changes and modifications can be madewithout departing from the spirit and scope of the present invention.Therefore, the present invention should not be construed as beinglimited to the description in the embodiments and examples.

Embodiment 1

In this embodiment, a carbazole compound according to one embodiment ofthe present invention will be described.

The carbazole compound according to one embodiment of the presentinvention is a carbazole compound represented by General Formula (G1).

Note that in General Formula (G1), R¹ represents any one of an alkylgroup having 1 to 12 carbon atoms, a substituted or unsubstituted phenylgroup, a substituted or unsubstituted biphenyl group, a substituted orunsubstituted naphthyl group, a substituted or unsubstituted phenanthrylgroup, a substituted or unsubstituted triphenylenyl group, and asubstituent represented by General Formula (G1-1). In General Formula(G1), R² represents any one of hydrogen, an alkyl group having 1 to 12carbon atoms, a substituted or unsubstituted phenyl group, a substitutedor unsubstituted biphenyl group, and a substituent represented byGeneral Formula (G1-2). In General Formula (G1), α³ represents either asubstituted or unsubstituted phenylene group or a substituted orunsubstituted biphenyldiyl group. In General Formula (G1), Ar³represents any one of a substituted or unsubstituted naphthyl group, asubstituted or unsubstituted phenanthryl group, and a substituted orunsubstituted triphenylenyl group.

Note that in General Formula (G1-1), Ar¹ represents any one of an alkylgroup having 1 to 12 carbon atoms, a substituted or unsubstituted phenylgroup, a substituted or unsubstituted biphenyl group, a substituted orunsubstituted naphthyl group, a substituted or unsubstituted phenanthrylgroup, and a substituted or unsubstituted triphenylenyl group. InGeneral Formula (G1-1), α¹ represents either a substituted orunsubstituted phenylene group or a substituted or unsubstitutedbiphenyldiyl group. In General Formula (G1-1), n represents 0 or 1.

Note that in General Formula (G1-2), Ar² represents any one of an alkylgroup having 1 to 12 carbon atoms, a substituted or unsubstituted phenylgroup, a substituted or unsubstituted biphenyl group, a substituted orunsubstituted naphthyl group, a substituted or unsubstituted phenanthrylgroup, and a substituted or unsubstituted triphenylenyl group. InGeneral Formula (G1-2), α² represents either a substituted orunsubstituted phenylene group or a substituted or unsubstitutedbiphenyldiyl group.

Note that a substituent which makes the HOMO level of a compound inwhich a bond of the substituent is substituted with hydrogen deep(absolute value is large) is used as each of the substituents in GeneralFormula (G1) (specifically, R¹, R², Ar³, and α³). Specifically, it ispreferable that the HOMO level of the compound in which the bond of thesubstituent in General Formula (G1) is substituted with hydrogen be lessthan or equal to −5.5 eV. Accordingly, the carbazole compound of thisembodiment that is represented by General Formula (G1) can have a deepHOMO level.

Further, a substituent which makes the band gap (Bg) and the T1 level ofa compound in which a bond of the substituent is substituted withhydrogen wide and high is used as each of the substituents in GeneralFormula (G1) (specifically, R¹, R², Ar³, and α³). Specifically, it ispreferable that the band gap of the compound in which the bond of thesubstituent in General Formula (G1) is substituted with hydrogen begreater than or equal to 2.7 eV (greater than or equal to the energy ofblue fluorescence, preferably greater than or equal to 3.0 eV) and thatthe T1 level of the compound be greater than or equal to 1.8 eV (greaterthan or equal to the energy of red phosphorescence). Accordingly, thecarbazole compound of this embodiment that is represented by GeneralFormula (G1) can have a wide band gap and a high T1 level. Therefore,when the carbazole compound of this embodiment is used as a hostmaterial of a light-emitting layer or a layer adjacent to thelight-emitting layer, a light-emitting element is probably able to emitlight more efficiently without taking excitation energy away from alight-emitting substance with high excitation energy. Further, in thecase where the carbazole compound of this embodiment is used as alight-emitting substance, light with a short wavelength (blue violet toblue) can be obtained.

Even if a material has a deep HOMO level, the material can maintain ashallow LUMO level as long as it has a wide band gap. Therefore, whenthe carbazole compound of this embodiment is used for a hole-transportlayer of a light-emitting element, electrons are probably able to beprevented from passing through an adjacent light-emitting layer, andrecombination of carriers in the light-emitting layer is probably ableto be performed efficiently.

For the above reason, a substituent which makes the LUMO level of acompound in which a bond of the substituent is substituted with hydrogenshallow (absolute value is small) is used as each of the substituents inGeneral Formula (G1) (specifically, R¹, R², Ar³, and α³). Specifically,it is preferable that the LUMO level of the compound in which the bondof the substituent in General Formula (G1) is substituted with hydrogenbe greater than or equal to −2.5 eV.

In the case where R¹, R², α³, and Ar³ further have substituents, thesubstituents are separately preferably any of an alkyl group having 1 to12 carbon atoms, a phenyl group, a biphenyl group, a naphthyl group, aphenanthryl group, and a triphenylenyl group in consideration of theHOMO level, the LUMO level, and the band gap.

In particular, Ar³ (Ar²) that is a part of the substituent connected tothe 3-position (6-position) of a carbazole skeleton is preferably acondensed ring such as a naphthyl group, a phenanthryl group, and atriphenylenyl group because such a condensed ring has an excellentcarrier-transport property. In particular, Ar³ (Ar²) is preferably anaphthyl group or a phenanthryl group. Further, Ar³ (Ar²) is preferablya phenanthryl group or a triphenylenyl group in terms of a highmolecular weight and an improvement in thermophysical property. Notethat naphthalene is a bicyclic condensed ring, and thus has a wide bandgap and a high T1 level. Although phenanthrylene or triphenylene is acondensed ring having three or more rings, phenanthrylene ortriphenylene has a wider band gap and a higher T1 level than anthracenethat is a tricyclic condensed ring or tetracene that is a tetracycliccondensed ring because phenanthrylene or triphenylene does not have apolyacene structure (the condensed ring is not straight) but has astructure in which helicene structures are combined (a condensed ring istwisted).

Further, arylene represented by α³ (α²) is preferably interposed betweenthe carbazole skeleton and Ar³ (Ar²), in which case conjugation hardlyextends from the carbazole skeleton to Ar³ (Ar²). In particular, aryleneis preferably bonded to the meta-position or the ortho-position (e.g.,the 1-position and the 3-position of phenylene, and 1-position and the2-position of phenylene), in which case extension of conjugation isprobably suppressed more and the band gap is probably increased. In thecase where arylene is bonded to the para-position, an excellentthermophysical property (high Tg) and an excellent carrier-transportproperty are probably obtained. Further, a phenyl skeleton or a biphenylskeleton, for example, is used so that α³ (α²) is an arylene group withsmall conjugation in order to prevent α³ (α²) itself from causingextension of conjugation.

A substituent connected to each of the substituents Ar¹, Ar², and Ar³ inGeneral Formula (G1) is preferably an alkyl group, in which case thecarbazole compound is easily dissolved in a solvent. In particular, amethyl group or a tert-butyl group is preferable because of itsexcellent solubility. In the case where the substituents Ar¹, Ar², andAr³ in General Formula (G1) have substituents such as an alkyl group oran aryl group, the structure of the carbazole compound of thisembodiment becomes more steric. As a result, it is likely thatcrystallization does not occur easily and concentration quenching due tostacked molecules, can be suppressed.

Further, in the case where the substituent R² in General Formula (G1) isa group other than hydrogen, the substituent R² and the substituentα³-Ar³ are preferably the same, in which case synthesis is performedmore easily. The substituent R² and the substituent α³-Ar³ arepreferably the same, in which case the molecular weight is increased,which results in an improvement in the thermophysical property. Notethat the substituent R² is preferably hydrogen, in which case the bandgap is wider and the T1 level is higher than those in the case where thesubstituent R² is a group other than hydrogen.

Specific examples of the substituent to be used will be described below.

As specific examples of the substituent represented by R¹ in GeneralFormula (G1), Structural Formulae (S-1) to (S-5), General Formula(G1-1), and the like are given.

Note that in General Formula (G1-1), Ar¹ represents any one of an alkylgroup having 1 to 12 carbon atoms, a substituted or unsubstituted phenylgroup, a substituted or unsubstituted biphenyl group, a substituted orunsubstituted naphthyl group, a substituted or unsubstituted phenanthrylgroup, and a substituted or unsubstituted triphenylenyl group. InGeneral Formula (G1-1), α¹ represents either a substituted orunsubstituted phenylene group or a substituted or unsubstitutedbiphenyldiyl group. In General Formula (G 1-1), n represents 0 or 1.

As specific examples of the substituent represented by R² in GeneralFormula (G1), Structural Formulae (S-11) to (S-16), General Formula(G1-2), and the like are given.

Note that in General Formula (G1-2), Ar² represents any one of an alkylgroup having 1 to 12 carbon atoms, a substituted or unsubstituted phenylgroup, a substituted or unsubstituted biphenyl group, a substituted orunsubstituted naphthyl group, a substituted or unsubstituted phenanthrylgroup, and a substituted or unsubstituted triphenylenyl group. InGeneral Formula (G1-2), α² represents either a substituted orunsubstituted phenylene group or a substituted or unsubstitutedbiphenyldiyl group.

As specific examples of the substituent represented by α³ in GeneralFormula (G1), α¹ in General Formula (G1-1), or α² in General Formula(G1-2), Structural Formulae (α-1) to (α-7) and the like are given.

As specific examples of the substituent represented by Ar¹ in GeneralFormula (G1-1) or Ar² in General Formula (G1-2), Structural Formulae(Ar-1) to (Ar-10) and the like are given.

As specific examples of the substituent represented by Ar³ in GeneralFormula (G1), Structural Formulae (Ar-11) to (Ar-15) and the like aregiven.

As specific examples of the carbazole compound represented by GeneralFormula (G1), carbazole compounds represented by Structural Formulae(100) to (131), (140) to (151), (160) to (183), and (190) to (197) canbe given. However, the present invention is not limited to these.

A variety of reactions can be applied to a synthesis method of thecarbazole compound of this embodiment. For example, the carbazolecompound of this embodiment can be synthesized by any of the synthesisreactions described in Synthesis Methods 1 to 3. Note that in reactionschemes described below, the description of General Formula (G1) can bereferred to for reference numerals that are not particularly explained(i.e., R¹, R², α³, and Ar³).

<Synthesis Method 1>

First, as shown in Reaction Scheme (A-1), a carbazole compound (a3) issynthesized by coupling of a halogenated carbazole compound (a1) and anarylboron compound (a2).

Note that X¹ represents halogen. X¹ preferably represents bromine, morepreferably iodine, which have high reactivity. B¹ represents boronicacid or dialkoxyboron.

Note that a variety of reaction conditions can be employed for thecoupling reaction in Reaction Scheme (A-1). As an example thereof, asynthesis method using a metal catalyst in the presence of a base can beemployed.

The case of using the Suzuki-Miyaura Reaction in Reaction Scheme (A-1)will be described. A palladium catalyst can be used as the metalcatalyst, and a mixture of a palladium complex and a ligand thereof canbe used as the palladium catalyst. As examples of the palladium complex,palladium(II) acetate, tetrakis(triphenylphosphine)palladium(0),bis(triphenylphosphine)palladium(II)dichloride, and the like are given.As examples of the ligand, tri(ortho-tolyl)phosphine,triphenylphosphine, tricyclohexylphosphine, and the like are given. Inaddition, as examples of the substance that can be used as the base, anorganic base such as sodium tert-butoxide, an inorganic base such aspotassium carbonate, and the like are given. The reaction is preferablyperformed in a solution. As examples of the solvent that can be used,the following are given: a mixed solvent of toluene and water; a mixedsolvent of toluene, an alcohol such as ethanol, and water; a mixedsolvent of xylene and water; a mixed solvent of xylene, an alcohol suchas ethanol, and water; a mixed solvent of benzene and water; a mixedsolvent of benzene, an alcohol such as ethanol, and water; a mixedsolvent of ethers such as ethyleneglycoldimethylether and water; and thelike. However, the catalyst, ligand, base, and solvent that can be usedare not limited thereto. Further, in Reaction Scheme (A-1), an arylaluminum compound, an aryl zirconium compound, an aryl zinc compound, anaryl tin compound, or the like may be used instead of the arylboroniccompound (a2). In addition, the reaction is preferably performed in aninert atmosphere of nitrogen, argon, or the like.

In Reaction Scheme (A-1), the case where the halogen group X¹ of thecompound (a1) and the boron compound group B¹ of the compound (a2) arereacted with each other is shown. However, the carbazole compound (a3)can be obtained even by coupling the compound (a1) as a boron compoundand the compound (a2) as a halide (with reaction groups X¹ and B¹replaced with each other).

Next, as shown in Reaction Scheme (A-2), a halogenated carbazolecompound (a4) is synthesized by halogenating the carbazole compound(a3).

Note that X² represents halogen. X² preferably represents bromine, morepreferably iodine, which have high reactivity.

A variety of reaction conditions can be employed for a halogenationreaction in Reaction Scheme (A-2). For example, a reaction in which ahalogenating agent is used in the presence of a polar solvent can beused. As the halogenating agent, N-bromosuccinimide (abbreviation: NBS),N-iodosuccinimide (abbreviation: NIS), bromine, iodine, potassiumiodide, or the like can be used. A bromide is preferably used as thehalogenating agent, in which case synthesis can be performed at lowcost. In addition, when an iodide is used as the halogenating agent, aniodine-substituted portion in a generated compound (i.e., an iodide) ishighly active. Thus, a reaction using the generated compound (i.e., theiodide) as a raw material is preferably performed, in which case thereaction proceeds more easily.

Next, as shown in Reaction Scheme (A-3), a carbazolyl boron compound(a5) is synthesized by reacting the compound activated by reaction ofthe halogenated carbazole compound (a4) with the metal catalyst with aboron compound.

Note that X² represents halogen. X² preferably represents bromine, morepreferably iodine, which have high reactivity. In addition, B²represents boronic acid or dialkoxyboron.

In Reaction Scheme (A-3), as an example of the activation of thehalogenated carbazole compound (a4), a lithiation reaction with an alkyllithium reagent can be used. As examples of the alkyl lithium reagent,n-butyllithium, tert-butyllithium, methyllithium, and the like aregiven. As acid, hydrochloric acid or the like can be used. As adehydrating solvent, an ether such as diethyl ether or tetrahydrofuran(THF) can be used. As examples of the boron compound that can be used,trimethyl borate, triethyl borate, and the like are given.

Next, as shown in Reaction Scheme (A-4), a halogenated carbazolecompound (a7) can be obtained by coupling a carbazolyl boron compound(a5) and a dihalogenated aryl compound (a6).

Note that X³ and X⁴ each represent halogen. Each of X³ and X⁴ preferablyrepresents bromine, more preferably iodine, which have high reactivity.In the case where B² and X³ are specifically reacted, halogen which hashigher reactivity than X⁴ is preferably used as X³. Note that inhalogen, bromine has higher reactivity than chlorine and iodine hashigher reactivity than bromine. B² represents boronic acid ordialkoxyboron.

A variety of reaction conditions can be employed for the couplingreaction in Reaction Scheme (A-4). As an example thereof, a synthesismethod using a metal catalyst in the presence of a base can be employed.Specifically, the coupling reaction can be performed in a manner similarto that in Reaction Scheme (A-1); therefore, the description given abovecan be referred to.

In Reaction Scheme (A-4), the case where the halogen group X³ of thecompound (a6) and the boron compound group B² of the compound (a5) arereacted with each other is shown. However, the carbazole compound (a7)can be obtained even by coupling the compound (a5) as a boron compoundand the compound (a6) as a halide (with reaction groups X³ and B²replaced with each other). Note that in this case, a halogen group whichhas higher reactivity than the halogen group X⁴ needs to be used as thehalogen group X³ in order to prevent reaction between the compounds(a6).

Next, as shown in Reaction Scheme (A-5), the carbazole compoundrepresented by General Formula (G1) can be obtained by coupling thehalogenated carbazole compound (a7) and an aryl boron compound (a8).

Note that X⁴ represents halogen. X⁴ preferably represents bromine, morepreferably iodine, which have high reactivity. B³ represents boronicacid or dialkoxyboron.

A variety of reaction conditions can be employed for the couplingreaction in Reaction Scheme (A-5). As an example thereof, a synthesismethod using a metal catalyst in the presence of a base can be employed.Specifically, the coupling reaction can be performed in a manner similarto that in Reaction Scheme (A-1); therefore, the description given abovecan be referred to.

In Reaction Scheme (A-5), the case where the halogenated group X⁴ of thecompound (a7) and the boron compound group B³ of the compound (a8) arereacted with each other is shown. However, the carbazole compoundrepresented by General Formula (G1) can be obtained even by coupling ofthe compound (a7) as a boron compound and the compound (a8) as a halide(with reaction groups X⁴ and B³ replaced with each other).

Further, in Reaction Schemes (A-1) to (A-5), the example in which thesubstituent-R² is combined with the 3-position of the carbazoleskeleton, and then the substituent-α³-Ar³ is combined with the6-position of the carbazole skeleton is shown. However, the presentinvention is not limited to the above reaction. The carbazole compoundrepresented by General Formula (G1) can be synthesized even by combiningthe substituent-R² after combining the substituent-α³-Ar³.

Note that the substituent-R² and the substituent-α³-Ar³ preferably havethe same skeleton, in which case a reaction in which the substituent R²and the substituent α³-Ar³ are combined with the 3-position and the6-position of the carbazole skeleton, respectively, at the same time isperformed easily.

Synthesis Method 2 will be described below as a synthesis method of thecarbazole compound of this embodiment, which is different from SynthesisMethod 1.

<Synthesis Method 2>

As shown in Reaction Scheme (B-1), the carbazole compound represented bygeneral Formula (G1) can be synthesized by coupling the halogenatedcarbazole compound (a4) and an aryl boron compound (a9).

Note that X² represents halogen. X² preferably represents bromine, morepreferably iodine, which have high reactivity. B⁴ represents boronicacid or dialkoxyboron.

A variety of reaction conditions can be employed for the couplingreaction in Reaction Scheme (B-1). As an example thereof, a synthesismethod using a metal catalyst in the presence of a base can be employed.Specifically, the coupling reaction can be performed in a manner similarto that in Reaction Scheme (A-1); therefore, the description given abovecan be referred to.

In Reaction Scheme (B-1), the case where the halogenated group X² of thecompound (a4) and the boron compound group B⁴ of the compound (a9) arereacted with each other is shown. However, the carbazole compoundrepresented by General Formula (G1) can be synthesized even by couplingthe compound (a4) as a boron compound and the compound (a9) as a halide(with reaction groups X² and B⁴ replaced with each other).

Further, in Reaction Scheme (B-1), the example in which thesubstituent-R² is combined with the 3-position of the carbazoleskeleton, and then the substituent-α³-Ar³ is combined with the6-position of the carbazole skeleton is shown. However, the presentinvention is not limited to the above reaction. The carbazole compoundrepresented by General Formula (G1) can be synthesized even by combiningthe substituent-R² after combining the substituent-α³-Ar³.

Note that the substituent-R² and the substituent-α³-Ar³ preferably havethe same skeleton, in which case a reaction in which the substituent-R²and the substituent-α³-Ar³ are combined with the 3-position and the6-position of the carbazole skeleton, respectively, at the same time canbe performed easily.

Synthesis Method 3 will be described below as a synthesis method of thecarbazole compound of this embodiment, which is different from SynthesisMethod 1 and Synthesis Method 2.

<Synthesis Method 3>

As shown in Reaction Scheme (C-1), the carbazole compound represented bygeneral Formula (G1) can be synthesized by coupling a carbazole compound(a10) and a halogenated aryl compound (a11).

Note that X⁵ represents halogen. X⁵ preferably represents bromine, morepreferably iodine, which have high reactivity.

A variety of reaction conditions can be employed for the couplingreaction in a coupling reaction of an aryl compound having a halogengroup and the 9-position of carbazole in Reaction Scheme (C-1). As anexample thereof, a synthesis method using a metal catalyst in thepresence of a base can be employed.

The case where the Buchwald-Hartwig reaction is performed in ReactionScheme (C-1) will be described. A palladium catalyst can be used as themetal catalyst, and a mixture of a palladium complex and a ligandthereof can be used as the palladium catalyst. As examples of thepalladium catalyst, bis(dibenzylideneacetone)palladium(0), palladium(II)acetate, and the like are given. As examples of the ligand,tri(tert-butyl)phosphine, tri(n-hexyl)phosphine, tricyclohexylphosphine,1,1-bis(diphenylphosphino)ferrocene (abbreviation: DPPF), and the likeare given. As a substance that can be used as the base, an organic basesuch as sodium tert-butoxide, an inorganic base such as potassiumcarbonate, and the like are given. In addition, this reaction ispreferably performed in a solution. As examples of the solvent that canbe used, toluene, xylene, benzene, and the like are given. However, thecatalyst, ligand, base, and solvent that can be used are not limitedthereto. Note that this reaction is preferably performed in an inertatmosphere of nitrogen, argon, or the like.

The case where the Ullmann reaction is performed in Reaction Scheme(C-1) is will be described. A copper catalyst can be used as a metalcatalyst, and copper(I) iodide and copper(II) acetate are given asexamples of the copper catalyst. As examples of the substance that canbe used as a base, inorganic bases such as potassium carbonate aregiven. The above reaction is preferably performed in a solution, and1,3-dimethyl-3,4,5,6-tetrahydro-2(1H)-pyrimidinone (abbreviation: DMPU),toluene, xylene, benzene, and the like are given as examples of thesolvent that can be used. However, the catalyst, ligand, base, andsolvent that can be used are not limited thereto. In addition, thisreaction is preferably performed under an inert atmosphere of nitrogen,argon, or the like.

Note that a solvent having a high boiling point such as DMPU or xyleneis preferably used because, by the Ullmann reaction, an object can beobtained in a shorter time and in a higher yield when the reactiontemperature is higher than or equal to 100° C. In particular, DMPU ismore preferable because the reaction temperature is more preferablygreater than or equal to 150° C.

Note that a reaction in which a substituent-R² and a substituent-α³-Ar³are combined with the 3-position and the 6-position of a carbazoleskeleton can be performed in a manner similar to that in ReactionSchemes (A-1) to (A-5) or Reaction Scheme (B-1). Therefore, the abovedescription can be referred to for the detail.

In the above manner, the carbazole compound of this embodiment can besynthesized.

The carbazole compound of this embodiment has a deep HOMO level (i.e.,the absolute value is large), and thus has an excellent property ofinjecting holes into a light-emitting layer. In addition, the carbazolecompound of this embodiment is electrochemically stable to oxidation.For these reasons, the carbazole compound of this embodiment can befavorably used as a material of a hole-transport layer of alight-emitting element. Further, a composite material in which thecarbazole compound of this embodiment (an electron donor) and anelectron acceptor are mixed can be used for a hole-injection layer of alight-emitting element. Note that the electron acceptor and the electrondonor are at least capable of donating and accepting electrons with theassistance of an electric field.

Further, the carbazole compound of this embodiment has a shallow LUMOlevel (i.e., the absolute value is small); thus, transfer of electronsto an anode can be blocked by using the carbazole compound as a materialof a hole-transport layer of a light-emitting element. Thus, theefficiency of the light-emitting element in which the carbazole compoundof this embodiment is used can be increased.

Further, the carbazole compound of this embodiment has a wide band gap;thus, energy transfer from a light-emitting layer can be suppressed evenin the case where the carbazole compound is used for a hole-transportlayer adjacent to a light-emitting layer. Thus, the lifetime as well asthe efficiency of the light-emitting element in which the carbazolecompound of this embodiment is used can be increased.

Further, the carbazole compound of this embodiment emits fluorescence,and thus can emit light with a short wavelength. Thus, the use of thecarbazole compound of this embodiment as a light-emitting material,light of blue-violet to blue can be obtained.

Further, the carbazole compound of this embodiment is also preferable asa host material of a light-emitting layer in a light-emitting element.In other words, when a light-emitting substance (hereinafter, alsoreferred to as a “dopant”) having a narrower band gap than the carbazolecompound of this embodiment is added to a layer formed of the carbazolecompound, light can be emitted from the dopant. At this time, even if afluorescent dopant which emits light with a relatively short wavelength,such as blue light, is used, light can be emitted efficiently from thedopant because the carbazole compound of this embodiment has a wide bandgap. In other words, the carbazole compound of this embodiment can beused as a host material of a compound which emits fluorescence in thevisible region. Further, in the case where a dopant is a phosphorescentcompound, a substance which has a higher T1 level than the dopant ispreferably used as a host material. The carbazole compound of thisembodiment has a high T1 level, and thus can be used as a host materialof a compound which emits phosphorescence in the visible region with awavelength longer than that of at least green light.

Further, the carbazole compound of this embodiment has weak absorptionof light in the visible region (approximately 380 nm to 750 nm), thetransmittance of visible light is high when a thin film is formed usingthe carbazole compound. Thus, the carbazole compound of this embodimentdoes not easily absorb emission energy even when used in alight-emitting element, which allows the light-emitting element to havea high external quantum yield.

This embodiment can be implemented in combination with any of the otherembodiments as appropriate.

Embodiment 2

In this embodiment, as one embodiment of the present invention, alight-emitting element in which the carbazole compound described inEmbodiment 1 is used will be described with reference to FIGS. 1A and1B.

In the light-emitting element of this embodiment, an EL layer includingat least a light-emitting layer is interposed between a pair ofelectrodes. The EL layer may have a plurality of layers in addition tothe light-emitting layer. The plurality of layers are stacked incombination of layers formed of substances having a highcarrier-injection property and a high carrier-transport property so thata light-emitting region is formed away from the electrodes, that is,carriers are recombined in a portion away from the electrodes. As theplurality of layers, for example, a hole-injection layer, ahole-transport layer, an electron-transport layer, an electron-injectionlayer, and the like may be included.

In the light-emitting element of this embodiment illustrated in FIG. 1A,an EL layer 102 is provided between a pair of electrodes, a firstelectrode 101 and a second electrode 103. In addition, the EL layer 102includes a hole-injection layer 111, a hole-transport layer 112, alight-emitting layer 113, an electron-transport layer 114, and anelectron-injection layer 115. Note that, in the light-emitting elementdescribed in this embodiment, the first electrode 101 provided over asubstrate 100 functions as an anode and the second electrode 103functions as a cathode.

A substrate 100 is used as a support of the light-emitting element. Forexample, glass, quartz, plastic, or the like can be used for thesubstrate 100. A flexible substrate may be used. A flexible substrate isa substrate that can be bent (is flexible). As examples of the flexiblesubstrate, plastic substrates made of polycarbonate, polyarylate, andpolyether sulfone, and the like are given. A film (made ofpolypropylene, polyester, vinyl, polyvinyl fluoride, vinyl chloride, orthe like), an inorganic film formed by evaporation, or the like can beused. Note that other materials may also be used as long as theyfunction as a support in a manufacturing process of the light-emittingelement.

For the first electrode 101, a metal, an alloy, an electricallyconductive compound, a mixture thereof, or the like which has a highwork function (specifically, a work function of 4.0 eV or more) ispreferably used. Specifically, for example, indium oxide-tin oxide (ITO:indium tin oxide), indium oxide-tin oxide including silicon or siliconoxide, indium oxide-zinc oxide (IZO: indium zinc oxide), indium oxideincluding tungsten oxide and zinc oxide (IWZO), and the like are given.Films of these conductive metal oxides are usually formed by sputtering,but may be formed by application of a sol-gel method or the like. Forexample, indium zinc oxide (IZO) can be formed by a sputtering methodusing a target in which zinc oxide is added to indium oxide at 1 wt % to20 wt %. Moreover, indium oxide containing tungsten oxide and zinc oxide(IWZO) can be formed by a sputtering method using a target in whichtungsten oxide is added to indium oxide at 0.5 wt % to 5 wt % and zincoxide is added to indium oxide at 0.1 wt % to 1 wt %. Besides, gold,platinum, nickel, tungsten, chromium, molybdenum, iron, cobalt, copper,palladium, nitride of a metal material (e.g., titanium nitride), and thelike are given.

Note that, in the EL layer 102, when a layer in contact with the firstelectrode 101 is formed using a composite material of an organiccompound and an electron acceptor (acceptor) described later, the firstelectrode 101 can be formed using any of a variety of metals, alloys,and electrically conductive compounds, a mixture thereof, and the likeregardless of the work function. For example, aluminum, silver, an alloycontaining aluminum (e.g., Al—Si), or the like can be used.

In the EL layer 102 formed over the first electrode 101, at least any ofthe hole-injection layer 111, the hole-transport layer 112, and thelight-emitting layer 113 contain the carbazole compound that is oneembodiment of the present invention. A known substance can be used forpart of the EL layer 102, and either a low molecular compound or a highmolecular compound can be used. Note that the substance used for formingthe EL layer 102 may have not only a structure formed of only an organiccompound but also a structure in which an inorganic compound ispartially contained.

The hole-injection layer 111 is a layer that contains a substance havinga high hole-injection property. As the substance having a highhole-injection property, for example, metal oxides such as molybdenumoxide, titanium oxide, vanadium oxide, rhenium oxide, ruthenium oxide,chromium oxide, zirconium oxide, hafnium oxide, tantalum oxide, silveroxide, tungsten oxide, and manganese oxide can be used. Aphthalocyanine-based compound such as phthalocyanine (abbreviation:H₂Pc), or copper(II) phthalocyanine (abbreviation: CuPc) can also beused.

Other examples of a substance that can be used are aromatic aminecompounds which are low molecular organic compounds, such as4,4′,4″-tris(N,N-diphenylamino)triphenylamine (abbreviation: TDATA),4,4′,4″-tris[N-(3-methylphenyl)-N-phenylamino]triphenylamine(abbreviation: MTDATA),4,4′-bis[N-(4-diphenylaminophenyl)-N-phenylamino]biphenyl (abbreviation:DPAB),4,4′-bis(N-{4-[N′-(3-methylphenyl)-N′-phenylamino]phenyl}-N-phenylamino)biphenyl(abbreviation: DNTPD),1,3,5-tris[N-(4-diphenylaminophenyl)-N-phenylamino]benzene(abbreviation: DPA3B),3-[N-(9-phenylcarbazol-3-yl)-N-phenylamino]-9-phenylcarbazole(abbreviation: PCzPCA1),3,6-bis[N-(9-phenylcarbazol-3-yl)-N-phenylamino]-9-phenylcarbazole(abbreviation: PCzPCA2), and3-[N-(1-naphthyl)-N-(9-phenylcarbazol-3-yl)amino]-9-phenylcarbazole(abbreviation: PCzPCN1).

Further, any of high molecular compounds (e.g., oligomers, dendrimers,or polymers) can be used. As examples of the high molecular compounds,the following are given: poly(N-vinylcarbazole) (abbreviation: PVK),poly(4-vinyltriphenylamine) (abbreviation: PVTPA),poly[N-(4-{N′-[4-(4-diphenylamino)phenyl]phenyl-N′-phenylamino}phenyl)methacrylamide](abbreviation: PTPDMA),poly[N,N′-bis(4-butylphenyl)-N,N′-bis(phenyl)benzidine] (abbreviation:Poly-TPD), and the like. A high molecular compound to which acid isadded, such as poly(3,4-ethylenedioxythiophene)/poly(styrenesulfonicacid) (PEDOT/PSS), or polyaniline/poly(styrenesulfonic acid) (PAni/PSS),can also be used.

A composite material in which an organic compound and an electronacceptor (acceptor) are mixed may be used for the hole-injection layer111. Such a composite material is excellent in a hole-injection propertyand a hole-transport property because holes are generated in the organiccompound by the electron acceptor. In this case, the organic compound ispreferably a material excellent in transporting the generated holes (asubstance having a high hole-transport property).

As the organic compound for the composite material, any of a variety ofcompounds such as aromatic amine compounds, carbazole derivatives,aromatic hydrocarbons, and high molecular compounds (e.g., oligomer,dendrimer, and polymer) can be used. The organic compound used for thecomposite material is preferably an organic compound having a highhole-transport property. Specifically, a substance having a holemobility of 10⁻⁶ cm²/Vs or higher is preferably used. Note that anyother substances may also be used as long as the hole-transport propertythereof is higher than the electron-transport property thereof. Theorganic compounds that can be used for the composite material will bespecifically given below.

The carbazole compound of one embodiment of the present invention is anorganic compound having a high hole-transport property, and thus can beused favorably for a composite material. Besides, as the organiccompound that can be used for the composite material, the following canbe used, for example: aromatic amine compounds such as TDATA, MTDATA,DPAB, DNTPD, DPA3B, PCzPCA1, PCzPCA2, PCzPCN1,4,4′-bis[N-(1-naphthyl)-N-phenylamino]biphenyl (abbreviation: NPB ora-NPD),N,N′-bis(3-methylphenyl)-N,N′-diphenyl-[1,1′-biphenyl]-4,4′-diamine(abbreviation: TPD), and4-phenyl-4′-(9-phenylfluoren-9-yl)triphenylamine (abbreviation: BPAFLP),and carbazole compounds such as 4,4′-di(N-carbazolyl)biphenyl(abbreviation: CBP), 1,3,5-tris[4-(N-carbazolyl)phenyl]benzene(abbreviation: TCPB), 9-[4-(10-phenyl-9-anthryl)phenyl]-9H-carbazole(abbreviation: CzPA),9-phenyl-3-[4-(10-phenyl-9-anthryl)phenyl]-9H-carbazole (abbreviation:PCzPA), and 1,4-bis[4-(N-carbazolyl)phenyl-2,3,5,6-tetraphenylbenzene.

Any of the following aromatic hydrocarbon compounds can be used:2-tert-butyl-9,10-di(2-naphthyl)anthracene (abbreviation: t-BuDNA),2-tert-butyl-9,10-di(1-naphthyl)anthracene,9,10-bis(3,5-diphenylphenyl)anthracene (abbreviation: DPPA),2-tert-butyl-9,10-bis(4-phenylphenyl)anthracene (abbreviation: t-BuDBA),9,10-di(2-naphthyl)anthracene (abbreviation: DNA),9,10-diphenylanthracene (abbreviation: DPAnth), 2-tert-butylanthracene(abbreviation: t-BuAnth), 9,10-bis(4-methyl-1-naphthyl)anthracene(abbreviation: DMNA),9,10-bis[2-(1-naphthyl)phenyl)-2-tert-butylanthracene,9,10-bis[2-(1-naphthyl)phenyl]anthracene,2,3,6,7-tetramethyl-9,10-di(1-naphthyl)anthracene, and the like.

Any of the following aromatic hydrocarbon compounds can be used:2,3,6,7-tetramethyl-9,10-di(2-naphthyl)anthracene, 9,9′-bianthryl,10,10′-diphenyl-9,9′-bianthryl,10,10′-bis(2-phenylphenyl)-9,9′-bianthryl,10,10′-bis[(2,3,4,5,6-pentaphenyl)phenyl]-9,9′-bianthryl, anthracene,tetracene, rubrene, perylene, 2,5,8,11-tetra(tert-butyl)perylene,pentacene, coronene, 4,4′-bis(2,2-diphenylvinyl)biphenyl (abbreviation:DPVBi), 9,10-bis[4-(2,2-diphenylvinyl)phenyl]anthracene (abbreviation:DPVPA), and the like.

As examples of the electron acceptor, organic compounds such as7,7,8,8-tetracyano-2,3,5,6-tetrafluoroquinodimethane (abbreviation:F₄-TCNQ) and chloranil; and transition metal oxides can be given. Oxidesof metals belonging to Groups 4 to 8 in the periodic table can be alsogiven. Specifically, vanadium oxide, niobium oxide, tantalum oxide,chromium oxide, molybdenum oxide, tungsten oxide, manganese oxide, andrhenium oxide are preferable because of their high electron-acceptingproperty. Among these, molybdenum oxide is particularly preferablebecause it is stable in the air, has a low hygroscopic property, and iseasily handled.

Note that the composite material may be formed using the above-describedelectron acceptor and the above high molecular compound such as PVK,PVTPA, PTPDMA, or Poly-TPD and may be used for the hole-injection layer111.

The hole-transport layer 112 is a layer that contains a substance havinga high hole-transport property. The carbazole compound of one embodimentof the present invention is a substance having a high hole-transportproperty, and thus can be favorably used as a material of thehole-transport layer 112.

The light-emitting layer 113 is a layer that contains a light-emittingsubstance. As the light-emitting substance, for example, a fluorescentcompound which emits fluorescence or a phosphorescent compound whichemits phosphorescence can be used.

The carbazole compound of one embodiment of the present invention is amaterial which exhibits fluorescence of blue-violet to blue, and thuscan also be used as a light-emitting substance.

Besides, as the fluorescent compound that can be used for thelight-emitting layer 113, a material for blue light emission, a materialfor green light emission, a material for yellow light emission, and amaterial for red light emission are given. As examples of the materialfor blue light emission, the following are given:N,N′-bis[4-(9H-carbazol-9-yl)phenyl]-N,N′-diphenylstilbene-4,4′-diamine(abbreviation: YGA2S),4-(9H-carbazol-9-yl)-4′-(10-phenyl-9-anthryl)triphenylamine(abbreviation: YGAPA),4-(10-phenyl-9-anthryl)-4′-(9-phenyl-9H-carbazol-3-yl)triphenylamine(abbreviation: PCBAPA), and the like. As examples of the material forgreen light emission, the following are given:N-(9,10-diphenyl-2-anthryl)-N,9-diphenyl-9H-carbazol-3-amine(abbreviation: 2PCAPA),N-[9,10-bis(1,1′-biphenyl-2-yl)-2-anthryl]-N,9-diphenyl-9H-carbazol-3-amine(abbreviation: 2PCABPhA),N-(9,10-diphenyl-2-anthryl)-N,N′-triphenyl-1,4-phenylenediamine(abbreviation: 2DPAPA),N-[9,10-bis(1,1′-biphenyl-2-yl)-2-anthryl]-N,N′-triphenyl-1,4-phenylenediamine(abbreviation: 2DPABPhA),N-[9,10-bis(1,1′-biphenyl-2-yl)]-N-[4-(9H-carbazol-9-yl)phenyl]-N-phenylanthracen-2-amine(abbreviation: 2YGABPhA), N,N,9-triphenylanthracen-9-amine(abbreviation: DPhAPhA), and the like. As examples of the material foryellow light emission, rubrene,5,12-bis(1,1′-biphenyl-4-yl)-6,11-diphenyltetracene (abbreviation: BPT),and the like are given. As examples of the material for red lightemission, N,N,N′,N′-tetrakis(4-methylphenyl)tetracene-5,11-diamine(abbreviation: p-mPhTD),7,14-diphenyl-N,N,N′,N′-tetrakis(4-methylphenyl)acenaphtho[1,2-a]fluoranthene-3,10-diamine(abbreviation: p-mPhAFD), and the like are given.

As the phosphorescent compound that can be used for the light-emittinglayer 703, a material for blue light emission, a material for greenlight emission, a material for yellow light emission, a material fororange light emission, and a material for red light emission are given.As examples of the material for blue light emission, the following aregiven:bis[2-(4′,6′-difluorophenyl)pyridinato-N,C^(2′)]iridium(III)tetrakis(1-pyrazolyl)borate(abbreviation: FIr6);bis[2-(4′,6′-difluorophenyl)pyridinato-N,C^(2′)]iridium(III)picolinate(abbreviation: FIrpic);bis{2-[3′,5′-bis(trifluoromethyl)phenyl]pyridinato-N,C^(2′)}iridium(III)picolinate (abbreviation: Ir(CF₃ppy)₂(pic));bis[2-(4′,6′-difluorophenyl)pyridinato-N,C^(2′)]iridium(III)acetylacetonate(abbreviation: FIr(acac)); and the like. As examples of the material forgreen light emission, the following are given:tris(2-phenylpyridinato-N,C^(2′))iridium(III) (abbreviation: Ir(ppy)₃),bis[2-phenylpyridinato-N,C^(2′)]iridium(III)acetylacetonate(abbreviation: Ir(ppy)₂(acac)),bis(1,2-diphenyl-1H-benzimidazolato)iridium(III)acetylacetonate(abbreviation: Ir(pbi)₂(acac)),bis(benzo[h]quinolinato)iridium(III)acetylacetonate (abbreviation:Ir(bzq)₂(acac)), tris(benzo[h]quinolinato)iridium(III) (abbreviation:Ir(bzq)₃), and the like. As examples of the material for yellow lightemission, the following are given:bis(2,4-diphenyl-1,3-oxazolato-N,C^(2′))iridium(III)acetylacetonate(abbreviation: Ir(dpo)₂(acac)),bis[2-(4′-perfluorophenylphenyl)pyridinato]iridium(III)acetylacetonate(abbreviation: Ir(p-PF-ph)₂(acac)),bis(2-phenylbenzothiazolato-N,C^(2′))iridium(III)acetylacetonate(abbreviation: Ir(bt)₂(acac))(acetylacetonato)bis[2,3-bis(4-fluorophenyl)-5-methylpyrazinato]iridium(III)(abbreviation: Ir(Fdppr-Me)₂(acac)),(acetylacetonato)bis{2-(4-methoxyphenyl)-3,5-dimethylpyrazinato}iridium(III)(abbreviation: Ir(dmmoppr)₂(acac)), and the like. As examples of thematerial for orange light emission, the following are given:tris(2-phenylquinolinato-N,C^(2′))iridium(III) (abbreviation: Ir(pq)₃),bis(2-phenylquinolinato-N,C^(2′))iridium(III)acetylacetonate(abbreviation: Ir(pq)₂(acac)),(acetylacetonato)bis(3,5-dimethyl-2-phenylpyrazinato)iridium(III)(abbreviation: [Ir(mppr-Me)₂(acac)]),(acetylacetonato)bis(5-isopropyl-3-methyl-2-phenylpyrazinato)iridium(III)(abbreviation: Ir(mppr-iPr)₂(acac)), and the like. As examples of thematerial for red light emission, organometallic complexes such asbis[2-(2′-benzo[4,5-α]thienyl)pyridinato-N,C^(3′))iridium(III)acetylacetonate(abbreviation: [Ir(btp)₂(acac)]),bis(1-phenylisoquinolinato-N,C^(2′))iridium(III)acetylacetonate(abbreviation: [Ir(piq)₂(acac)]),(acetylacetonato)bis[2,3-bis(4-fluorophenyl)quinoxalinato]iridium(III)(abbreviation: [Ir(Fdpq)₂(acac)]),(acetylacetonato)bis(2,3,5-triphenylpyrazinato)iridium(III)(abbreviation: [Ir(tppr)₂(acac)]),(dipivaloylmethanato)bis(2,3,5-triphenylpyrazinato)iridium(III)(abbreviation: [Ir(tppr)₂(dpm)]), and(2,3,7,8,12,13,17,18-octaethyl-21H,23H-porphyrin)platinum(II)(abbreviation: PtOEP). In addition, rare-earth metal complexes, such astris(acetylacetonato)(monophenanthroline)terbium(III) (abbreviation:Tb(acac)₃(Phen)),tris(1,3-diphenyl-1,3-propanedionato)(monophenanthroline)europium(III)(abbreviation: Eu(DBM)₃(Phen)), andtris[1-(2-thenoyl)-3,3,3-trifiuoroacetonato](monophenanthroline)europium(III)(abbreviation: Eu(TTA)₃(Phen)), exhibit light emission from rare-earthmetal ions (electron transition between different multiplicities), andthus can be used as phosphorescent compounds.

A high molecular compound can be used as the light-emitting substance.Specifically, a material for blue light emission, a material for greenlight emission, and a material for orange to red light emission aregiven. As examples of the material for blue light emission, thefollowing are given: poly(9,9-dioctylfluorene-2,7-diyl) (abbreviation:PFO),poly[(9,9-dioctylfluorene-2,7-diyl-co-(2,5-dimethoxybenzene-1,4-diyl)](abbreviation: PF-DMOP), poly{(9,9-dioctylfluorene-2,7-diyl)-co-[N,N′-di-(p-butylphenyl)-1,4-diaminobenzene]}(abbreviation: TAB-PFH), and the like. As examples of the material forgreen light emission, the following are given: poly(p-phenylenvinylene)(abbreviation: PPV),poly[(9,9-dihexylfluorene-2,7-diyl)-alt-co-(benzo[2,1,3]thiadiazol-4,7-diyl)](abbreviation: PFBT),poly[(9,9-dioctyl-2,7-divinylenfluorenylene)-alt-co-(2-methoxy-5-(2-ethylhexyloxy)-1,4-phenylene)],and the like. As examples of the material for orange to red lightemission, the following are given:poly[2-methoxy-5-(2′-ethylhexoxy)-1,4-phenylenevinylene] (abbreviation:MEH-PPV), poly(3-butylthiophene-2,5-diyl) (abbreviation: R4-PAT),poly{[9,9-dihexyl-2,7-bis(1-cyanovinylene)fluorenylene]-alt-co-[2,5-bis(N,N′-diphenylamino)-1,4-phenylene]}, poly{[2-methoxy-5-(2-ethylhexyloxy)-1,4-bis(1-cyanovinylenephenylene)]-alt-co-[2,5-bis(N,N′-diphenylamino)-1,4-phenylene]}(abbreviation: CN-PPV-DPD), and the like.

Note that the light-emitting layer 113 may have a structure in which theabove light-emitting substance (a guest material) is dispersed inanother substance (a host material). As a host material, a variety ofkinds of materials can be used, and it is preferable to use a substancewhich has a higher lowest unoccupied molecular orbital level (LUMOlevel) than the light-emitting material and has a lower highest occupiedmolecular orbital level (HOMO level) than the light-emitting material.

The carbazole compound of one embodiment of the present invention has awide band gap (the S1 level is high), and thus can also be usedfavorably as a host material of the light-emitting layer 113.

In the case where a light-emitting substance is a phosphorescentcompound, a substance which has a higher T1 level than thelight-emitting substance is preferably used as a host material of thelight-emitting substance.

The carbazole compound of one embodiment of the present invention has ahigh T1 level, and thus can also be used favorably as a host material ofa phosphorescent substance.

As specific examples of the host material that can be used in additionto the above, the following are given: metal complexes such astris(8-quinolinolato)aluminum(III) (abbreviation: Alq),tris(4-methyl-8-quinolinolato)aluminum(III) (abbreviation: Almq₃),bis(10-hydroxybenzo[h]quinolinato)beryllium(II) (abbreviation: BeBq₂),bis(2-methyl-8-quinolinolato)(4-phenylphenolato)aluminum(III)(abbreviation: BAlq), bis(8-quinolinolato)zinc(II) (abbreviation: Znq),bis[2-(2-benzoxazolyl)phenolato]zinc(II) (abbreviation: ZnPBO), andbis[2-(2-benzothiazolyl)phenolato]zinc(II) (abbreviation: ZnBTZ);heterocyclic compounds such as2-(4-biphenylyl)-5-(4-tert-butylphenyl)-1,3,4-oxadiazole (abbreviation:PBD), 1,3-bis[5-(p-tert-butylphenyl)-1,3,4-oxadiazol-2-yl]benzene(abbreviation: OXD-7),3-(4-biphenylyl)-4-phenyl-5-(4-tert-butylphenyl)-1,2,4-triazole(abbreviation: TAZ),2,2′,2″-(1,3,5-benzenetriyl)tris(1-phenyl-1H-benzimidazole)(abbreviation: TPBI), bathophenanthroline (abbreviation: BPhen), andbathocuproine (BCP); condensed aromatic compounds such as9-[4-(10-phenyl-9-anthryl)phenyl]-9H-carbazole (abbreviation: CzPA),3,6-diphenyl-9-[4-(10-phenyl-9-anthryl)phenyl]-9H-carbazole(abbreviation: DPCzPA), 9,10-bis(3,5-diphenylphenyl)anthracene(abbreviation: DPPA), 9,10-di(2-naphthyl)anthracene (abbreviation: DNA),2-tert-butyl-9,10-di(2-naphthyl)anthracene (abbreviation: t-BuDNA),9,9′-bianthryl (abbreviation: BANT),9,9′-(stilbene-3,3′-diyl)diphenanthrene (abbreviation: DPNS),9,9′-(stilbene-4,4′-diyl)diphenanthrene (abbreviation: DPNS2),3,3′,3″-(benzene-1,3,5-triyl)tripyrene (abbreviation: TPB3),9,10-diphenylanthracene (abbreviation: DPAnth), and6,12-dimethoxy-5,11-diphenylchrysene; aromatic amine compounds such asN,N-dipheyl-9-[4-(10-phenyl-9-anthryl)phenyl]-9H-carbazol-3-amine(abbreviation: CzA1PA), 4-(10-phenyl-9-anthryl)triphenylamine(abbreviation: DPhPA),N,9-diphenyl-N-[4-(10-phenyl-9-anthryl)phenyl]-9H-carbazol-3-amine(abbreviation: PCAPA),N,9-diphenyl-N-{4-[4-(10-phenyl-9-anthryl)phenyl]phenyl}-9H-carbazol-3-amine(abbreviation: PCAPBA),N-(9,10-diphenyl-2-anthryl)-N,9-diphenyl-9H-carbazol-3-amine(abbreviation: 2PCAPA), NPB (or α-NPD), TPD, DFLDPBi, and BSPB; and thelike.

Plural kinds of materials can be used as the host material. For example,in order to suppress crystallization, a substance such as rubrene whichsuppresses crystallization may be further added. In addition, NPB, Alq,or the like may be further added in order to efficiently transfer energyto the guest material.

When the structure in which a guest material is dispersed in a hostmaterial is employed, crystallization of the light-emitting layer 113can be suppressed. In addition, concentration quenching due to highconcentration of the guest material can be suppressed.

The electron-transport layer 114 is a layer that contains a substancehaving a high electron-transport property. As examples of the substancehaving a high electron-transport property, the following are given:metal complexes having a quinoline skeleton or a benzoquinolineskeleton, such as tris(8-quinolinolato)aluminum (abbreviation: Alq),tris(4-methyl-8-quinolinolato)aluminum (abbreviation: Almq₃),bis(10-hydroxybenzo[h]-quinolinato)beryllium (abbreviation: BeBq₂), andbis(2-methyl-8-quinolinolato)(4-phenylphenolato)aluminum (abbreviation:BAlq). A metal complex or the like including an oxazole-based orthiazole-based ligand, such as bis[2-(2-hydroxyphenyl)benzoxazolato]zinc(abbreviation: Zn(BOX)₂) or bis[2-(2-hydroxyphenyl)benzothiazolato]zinc(abbreviation: Zn(BTZ)₂) can also be used. Besides the metal complexes,2-(4-biphenylyl)-5-(4-tert-butylphenyl)-1,3,4-oxadiazole (abbreviation:PBD), 1,3-bis[5-(p-tert-butylphenyl)-1,3,4-oxadiazol-2-yl]benzene(abbreviation: OXD-7),3-(4-biphenylyl)-4-phenyl-5-(4-tert-butylphenyl)-1,2,4-triazole(abbreviation: TAZ), bathophenanthroline (abbreviation: BPhen),bathocuproine (abbreviation: BCP), or the like can also be used. Thesubstances given here are mainly ones that have an electron mobility of10⁻⁶ cm²/V·s or higher. Note that the electron-transport layer is notlimited to a single layer and may be a stack of two or more layerscontaining any of the above substances.

The electron-injection layer 115 is a layer that contains a substancehaving a high electron-injection property. For the electron-injectionlayer 115, an alkali metal, an alkaline earth metal, or a compoundthereof, such as lithium, cesium, calcium, lithium fluoride, cesiumfluoride, calcium fluoride, or lithium oxide, can be used. A rare earthmetal compound such as erbium fluoride can also be used. Any of theabove substances for forming the electron-transport layer 114 can alsobe used.

Alternatively, a composite material in which an organic compound and anelectron donor (donor) are mixed may be used for the electron-injectionlayer 115. Such a composite material is excellent in anelectron-injection property and an electron-transport property becauseelectrons are generated in the organic compound by the electron donor.In this case, the organic compound is preferably a material excellent intransporting the generated electrons. Specifically, the above-describedmaterials for forming the electron-transport layer 114 (e.g., a metalcomplex or a heteroaromatic compound) can be used for example. As theelectron donor, a substance exhibiting an electron-donating property tothe organic compound may be used. It is preferable to use an alkalimetal, an alkaline-earth metal, or a rare earth metal, such as lithium,cesium, magnesium, calcium, erbium, or ytterbium. In addition, it ispreferable to use an alkali metal oxide or an alkaline-earth metaloxide, such as lithium oxide, calcium oxide, or barium oxide. Lewis basesuch as magnesium oxide can also be used. An organic compound such astetrathiafulvalene (abbreviation: TTF) can also be used.

Note that the hole-injection layer 111, the hole-transport layer 112,the light-emitting layer 113, the electron-transport layer 114, and theelectron-injection layer 115 which are described above can each beformed by a method such as an evaporation method (e.g., a vacuumevaporation method), an ink-jet method, or a coating method.

When the second electrode 103 functions as a cathode, it can be formedusing a metal, an alloy, an electrically-conductive compound, a mixturethereof, or the like having a low work function (preferably, a workfunction of 3.8 eV or less). Specifically, any of the following can beused: aluminum or silver; an element belonging to Group 1 or Group 2 ofthe periodic table, that is, an alkali metal such as lithium or cesiumor an alkaline earth metal such as magnesium, calcium, or strontium; analloy of the above metals (e.g., Mg—Ag or Al—Li); a rare earth metalsuch as europium or ytterbium; an alloy of the above metals; or thelike.

Note that, in the case where in the EL layer 102, a layer formed incontact with the second electrode 103 is formed using a compositematerial in which the organic compound and the electron donor, which aredescribed above, are mixed, a variety of conductive materials such asaluminum, silver, ITO, and indium tin oxide containing silicon orsilicon oxide can be used regardless of the work function.

Note that the second electrode 103 can be formed by a vacuum evaporationmethod or a sputtering method. In the case of using a silver paste orthe like, a coating method, an inkjet method, or the like can be used.

In the above light-emitting element, current flows due to a potentialdifference generated between the first electrode 101 and the secondelectrode 103 and holes and electrons recombine in the EL layer 102,whereby light is emitted. Then, this emitted light is extracted throughone or both of the first electrode 101 and the second electrode 103.Therefore, one or both of the first electrode 101 and the secondelectrode 103 is/are an electrode having a property of transmittingvisible light.

Note that the structure of the layer provided between the firstelectrode 101 and the second electrode 103 is not limited to the abovestructure. A structure other than the above may also be employed as longas a light-emitting region in which holes and electrons recombine isprovided in a portion away from the first electrode 101 and the secondelectrode 103 in order to prevent quenching due to proximity of thelight-emitting region to a metal.

In other words, a stacked structure of the layer is not particularlylimited, and a layer formed of a substance having a highelectron-transport property, a substance having a high hole-transportproperty, a substance having a high electron-injection property, asubstance having a high hole-injection property, a bipolar substance (asubstance having a high electron-transport property and a highhole-transport property), a hole-blocking material, or the like mayfreely be combined with a light-emitting layer.

In a light-emitting element illustrated in FIG. 1B, the EL layer 102 isprovided between the first electrode 101 and the second electrode 103over the substrate 100. The EL layer 102 includes a hole-injection layer111, a hole-transport layer 112, the light-emitting layer 113, anelectron-transport layer 114, and an electron-injection layer 115. Thelight-emitting element in FIG. 1B includes: the second electrode 103serving as a cathode over the substrate 100; the electron-injectionlayer 115, the electron-transport layer 114, the light-emitting layer113, the hole-transport layer 112, and the hole-injection layer 111which are stacked over the second electrode 103 in this order; and thefirst electrode 101 serving as an anode over the hole-injection layer111.

Further, the HOMO level of the carbazole compound of one embodiment ofthe present invention is deep and the LUMO level thereof is shallow. Inaddition, the carbazole compound has a wide band gap. For these reasons,the carbazole compound can be favorably used as a carrier-transportlayer adjacent to a light-emitting layer (e.g., a hole-transport layer,an electron-transport layer, or a hole-blocking layer). The use of thecarbazole compound allows an element with high efficiency to beobtained.

A specific manufacturing method of a light-emitting element will bedescribed below.

The light-emitting element of this embodiment has a structure in whichan EL layer is interposed between a pair of electrodes. The electrode(the first electrode or the second electrode) and the EL layer may beformed by a wet process such as a droplet discharging method (an ink-jetmethod), a spin coating method, or a printing method, or by a dryprocess such as a vacuum evaporation method, a CVD method, or asputtering method. The use of a wet process enables formation atatmospheric pressure with a simple device and by a simple process, whichgives effects of simplifying the process and improving productivity. Incontrast, a dry process does not need dissolution of a material andenables use of a material that has low solubility in a solution, whichexpands the range of material choices.

All the thin films included in the light-emitting element may be formedby a wet method. In this case, the light-emitting element can bemanufactured with only facilities needed for a wet process.Alternatively, formation of the stacked layers up to formation of thelight-emitting layer may be performed by a wet process whereas thefunctional layer, the first electrode, and the like which are stackedover the light-emitting layer may be formed by a dry process. Furtheralternatively, the second electrode and the functional layer may beformed by a dry process before the formation of the light-emitting layerwhereas the light-emitting layer, the functional layer stackedthereover, and the first electrode may be formed by a wet process.Needless to say, this embodiment is not limited to this, and thelight-emitting element can be formed by appropriate selection from a wetmethod and a dry method depending on a material to be used, filmthickness that is necessary, and the interface state.

As described above, the light-emitting element can be manufactured usingthe carbazole compound of one embodiment of the present invention.According to one embodiment of the present invention, a light-emittingelement with high emission efficiency can be obtained. In addition, alight-emitting element with long lifetime can be obtained.

Further, a light-emitting device (such as an image display device) usingthe light-emitting element of one embodiment of the present invention,which is manufactured as described above, can have low powerconsumption.

Note that by use of a light-emitting element described in thisembodiment, a passive matrix light-emitting device or an active matrixlight-emitting device in which driving of the light-emitting element iscontrolled by a thin film transistor (TFT) can be manufactured.

This embodiment can be implemented in appropriate combination with anyof the other embodiments.

Embodiment 3

In this embodiment, a mode of a light-emitting element having astructure in which a plurality of light-emitting units are stacked(hereinafter, referred to as a stacked-type element) will be describedwith reference to FIGS. 2A and 2B. This light-emitting element is alight-emitting element including a plurality of light-emitting unitsbetween a first electrode and a second electrode.

In FIG. 2A, a first light-emitting unit 311 and a second light-emittingunit 312 are stacked between a first electrode 301 and a secondelectrode 303. In this embodiment, the first electrode 301 functions asan anode and the second electrode 303 functions as a cathode. The firstelectrode 301 and the second electrode 303 can be the same as those inEmbodiment 2. Further, the first light-emitting unit 311 and the secondlight-emitting unit 312 may have the same structure or differentstructures. The first light-emitting unit 311 and the secondlight-emitting unit 312 may have the same structure as in Embodiment 2,or either of the units may have a structure different from that inEmbodiment 2.

Further, a charge generation layer 313 is provided between the firstlight-emitting unit 311 and the second light-emitting unit 312. Thecharge generation layer 313 functions so that electrons are injectedinto one light-emitting unit and holes are injected into the otherlight-emitting unit by application of voltage between the firstelectrode 301 and the second electrode 303. In this embodiment, whenvoltage is applied to the first electrode 301 so that the potentialthereof is higher than that of the second electrode 303, the chargegeneration layer 313 injects electrons into the first light-emittingunit 311 and injects holes into the second light-emitting unit 312.

Note that the charge generation layer 313 preferably has a property oftransmitting visible light in terms of light extraction efficiency.Further, the charge generation layer 313 functions even when it haslower conductivity than the first electrode 301 or the second electrode303.

The charge generation layer 313 may have either a structure including anorganic compound having a high hole-transport property and an electronacceptor or a structure including an organic compound having a highelectron-transport property and an electron donor. Alternatively, bothof these structures may be stacked. Note that the electron acceptor andthe electron donor are at least capable of donating and acceptingelectrons with the assistance of an electric field.

In the case of a structure in which an electron acceptor is added to anorganic compound having a high hole-transport property, as the organiccompound having a high hole-transport property, the carbazole compoundof one embodiment of the present invention can be used. Besides, anaromatic amine compound such as NPB, TPD, TDATA, MTDATA, or4,4′-bis[N-(spiro-9,9′-bifluoren-2-yl)-N-phenylamino]biphenyl(abbreviation: BSPB), or the like can be used. The substances mentionedhere are mainly ones that have a hole mobility of 10⁻⁶ cm²/V·s orhigher. Note that substances other than the above substances may be usedas long as they are organic compounds whose hole-transport propertiesare higher than the electron-transport properties.

As examples of the electron acceptor,7,7,8,8-tetracyano-2,3,5,6-tetrafluoroquinodimethane (abbreviation:F₄-TCNQ), chloranil, and the like can be given. In addition, atransition metal oxide can be given. Oxides of metals belonging toGroups 4 to 8 in the periodic table can be also given. Specifically,vanadium oxide, niobium oxide, tantalum oxide, chromium oxide,molybdenum oxide, tungsten oxide, manganese oxide, and rhenium oxide arepreferable because of their high electron-accepting property. Amongthese, molybdenum oxide is particularly preferable because it is stablein the air, has a low hygroscopic property, and is easily handled.

In contrast, in the case of the structure in which an electron donor isadded to an organic compound having a high electron-transport property,as the organic compound having a high electron-transport property, ametal complex having a quinoline skeleton or a benzoquinoline skeleton,such as Alq, Almq₃, BeBq₂, or BAlq, or the like can be used, forexample. Alternatively, a metal complex having an oxazole-based ligandor a thiazole-based ligand, such as Zn(BOX)₂ or Zn(BTZ)₂ can be used.Alternatively, in addition to such a metal complex, PBD, OXD-7, TAZ,BPhen, BCP, or the like can be used. The substances mentioned here aremainly ones that have an electron mobility of 10⁻⁶ cm²/V·s or higher.Note that substances other than the above substances may be used as longas they are organic compounds whose electron-transport properties arehigher than the hole-transport properties.

Further, as the electron donor, an alkali metal, an alkaline earthmetal, a rare earth metal, a metal belonging to Group 13 of the periodictable, or an oxide or carbonate thereof can be used. Specifically,lithium, cesium, magnesium, calcium, ytterbium, indium, lithium oxide,cesium carbonate, or the like is preferably used. Alternatively, anorganic compound such as tetrathianaphthacene may be used as theelectron donor.

Note that formation of the charge generation layer 313 using any of theabove materials makes it possible to suppress an increase in drivevoltage caused when the EL layers are stacked.

In this embodiment, the light-emitting element having two light-emittingunits is described, and one embodiment of the present invention can besimilarly applied to a light-emitting element having a stack of three ormore light-emitting units as illustrated in FIG. 2B. A plurality oflight-emitting units which are partitioned by a charge generation layerare arranged between a pair of electrodes, as in the light-emittingelement according to this embodiment, whereby it is possible to providea light-emitting element which has long lifetime and is able to emitlight with luminance while current density is kept low.

Further, when emission colors of the light-emitting units are madedifferent, light emission having a desired color can be obtained fromthe light-emitting element as a whole. For example, in thelight-emitting element having two light-emitting units, when an emissioncolor of the first light-emitting unit and an emission color of thesecond light-emitting unit are made to be complementary colors, it ispossible to obtain a light-emitting element from which white light isemitted from the whole light-emitting element. Note that “complementarycolors” refer to colors that can produce an achromatic color when mixed.In other words, when lights obtained from substances which emitcomplementary colors are mixed, white emission can be obtained. This canbe applied to a light-emitting element having three or morelight-emitting units. For example, when the first light-emitting unitemits red light, the second light-emitting unit emits green light, andthe third light-emitting unit emits blue light, white light can beemitted from the whole light-emitting element.

Note that this embodiment can be freely combined with any of the otherembodiments.

Embodiment 4

In this embodiment, a light-emitting device having a light-emittingelement of one embodiment of the present invention will be describedwith reference to FIGS. 3A and 3B. FIG. 3A is a top view illustrating alight-emitting device. FIG. 3B is a cross-sectional view taken alonglines A-B and C-D in FIG. 3A.

In FIG. 3A, reference numeral 401 denotes a driver circuit portion (asource side driver circuit), reference numeral 402 denotes a pixelportion, and reference numeral 403 denotes a driver circuit portion (agate side driver circuit), which are shown by a dotted line. Referencenumeral 404 denotes a sealing substrate, reference numeral 405 denotes asealant, and a portion enclosed by the sealant 405 is a space.

Note that a lead wiring 408 is a wiring for transmitting signals thatare to be input to the source side driver circuit 401 and the gate sidedriver circuit 403, and receives a video signal, a clock signal, a startsignal, a reset signal, and the like from a flexible printed circuit(FPC) 409 which serves as an external input terminal. Although only theFPC is illustrated here, a printed wiring board (PWB) may be attached tothe FPC. The light-emitting device in this specification includes, inits category, not only the light-emitting device itself but also thelight-emitting device provided with the FPC or the PWB.

Next, the cross-sectional structure will be described with reference toFIG. 3B. The driver circuit portion and the pixel portion are formedover an element substrate 410. Here, one pixel in the pixel portion 402and the source side driver circuit 401 which is the driver circuitportion are illustrated.

Note that as the source side driver circuit 401, a CMOS circuit which isobtained by combining an n-channel TFT 423 and a p-channel TFT 424 isformed. The driver circuit may be any of a variety of circuits formedwith TFTs, such as a CMOS circuit, a PMOS circuit, or an NMOS circuit.Although a driver-integrated type in which a driver circuit is formedover the substrate is described in this embodiment, the presentinvention is not limited to this type, and the driver circuit can beformed outside the substrate.

The pixel portion 402 includes a plurality of pixels having a switchingTFT 411, a current control TFT 412, and a first electrode 413electrically connected to a drain of the current control TFT 412. Aninsulator 414 is formed to cover an end portion of the first electrode413. Here, the insulator 414 is formed using a positive photosensitiveacrylic resin film.

In order to improve the coverage, the insulator 414 is provided suchthat either an upper end portion or a lower end portion of the insulator414 has a curved surface with a curvature. For example, when positivetype photosensitive acrylic is used as a material for the insulator 414,the insulator 414 preferably has a curved surface with a curvatureradius (0.2 μm to 3 μm) only as the upper end. The insulator 414 can beformed using either a negative type which becomes insoluble in anetchant by light irradiation or a positive type which becomes soluble inan etchant by light irradiation.

An EL layer 416 and a second electrode 417 are formed over the firstelectrode 413. Here, a material having a high work function ispreferably used as a material for forming the first electrode 413functioning as the anode. For example, it is possible to use a singlelayer of an ITO film, an indium tin oxide film that includes silicon, anindium oxide film that contains 2 wt % to 20 wt % of zinc oxide, atitanium nitride film, a chromium film, a tungsten film, a Zn film, a Ptfilm, or the like, a stacked layer of a titanium nitride film and a filmthat mainly contains aluminum, a three-layer structure of a titaniumnitride film, a film that mainly contains aluminum and a titaniumnitride film, or the like. Note that, a stacked structure allowsresistance of a wiring to be low and a good ohmic contact to beobtained.

The EL layer 416 is formed by any of a variety of methods such as anevaporation method using an evaporation mask, a droplet dischargingmethod like an inkjet method, a printing method, and a spin coatingmethod. The EL layer 416 contains the carbazole compound described inEmbodiment 1. Further, another material included in the EL layer 416 maybe a low molecular material, an oligomer, a dendrimer, a high molecularmaterial, or the like.

It is preferable to use a material having a low work function (e.g., Al,Mg, Li, Ca, or an alloy or compound thereof such as Mg—Ag, Mg—In, orAl—Li) as a material used for the second electrode 417 which is formedover the EL layer 416 and functions as a cathode. In order that lightgenerated in the EL layer 416 be transmitted through the secondelectrode 417, the second electrode 417 may be formed of a stack of ametal thin film having a reduced thickness and a transparent conductivefilm (e.g., ITO, indium oxide containing 2 wt % to 20 wt % of zincoxide, indium oxide-tin oxide that includes silicon or silicon oxide, orzinc oxide (ZnO)).

The sealing substrate 404 is attached to the element substrate 410 withthe sealant 405; thus, a light-emitting element 418 is provided in thespace 407 enclosed by the element substrate 410, the sealing substrate404, and the sealant 405. Note that the space 407 may be filled withfiller such as an inert gas (e.g., nitrogen or argon) or with thesealant 405.

Note that an epoxy-based resin is preferably used as the sealant 405. Itis preferable that the material do not transmit moisture or oxygen asmuch as possible. As a material used for the sealing substrate 404, aplastic substrate formed of FRP (fiberglass-reinforced plastics), PVF(polyvinyl fluoride), polyester, acrylic, or the like can be used otherthan a glass substrate or a quartz substrate.

As described above, the active matrix light-emitting device includingthe light-emitting element of one embodiment of the present inventioncan be obtained.

Further, a light-emitting element of one embodiment of the presentinvention can be used for a passive matrix light-emitting device as wellas the above active matrix light-emitting device. FIGS. 4A and 4Billustrate a perspective view and a cross-sectional view of a passivematrix light-emitting device using a light-emitting element of oneembodiment of the present invention. FIG. 4A is a perspective view ofthe light-emitting device. FIG. 4B is a cross-sectional view taken alonga line X-Y in FIG. 4A.

In FIGS. 4A and 4B, an EL layer 504 is provided between a firstelectrode 502 and a second electrode 503 over a substrate 501. An endportion of the first electrode 502 is covered with an insulating layer505. In addition, a partition layer 506 is provided over the insulatinglayer 505. The sidewalls of the partition layer 506 slope so that thedistance between one sidewall and the other sidewall gradually decreasestoward the surface of the substrate. In other words, a cross sectiontaken along the direction of the short side of the partition layer 506is trapezoidal, and the lower side (a side in contact with theinsulating layer 505 which is one of a pair of parallel sides of thetrapezoidal cross section) is shorter than the upper side (a side not incontact with the insulating layer 505 which is the other of the pair ofparallel sides). With the partition layer 506 provided in such a way, adefect of a light-emitting element due to crosstalk or the like can beprevented.

Thus, the passive matrix light-emitting device including alight-emitting element of one embodiment of the present invention can beobtained.

The light-emitting devices described in this embodiment (the activematrix light-emitting device and the passive matrix light-emittingdevice) are both manufactured using the light-emitting element of oneembodiment of the present invention, thereby having low powerconsumption.

Note that this embodiment can be freely combined with any of the otherembodiments as appropriate.

Embodiment 5

In this embodiment, examples of a variety of electronic devices andlighting devices, which are completed using the light-emitting device ofone embodiment of the present invention, will be described withreference FIGS. 5A to 5E and FIG. 6.

Examples of the electronic devices to which the light-emitting device isapplied include television devices (also referred to as TV or televisionreceivers), monitors for computers and the like, cameras such as digitalcameras and digital video cameras, digital photo frames, cellular phones(also referred to as portable telephone devices), portable gamemachines, portable information terminals, audio playback devices, largegame machines such as pin-ball machines, and the like. Specific examplesof these electronic devices and a lighting device are illustrated inFIGS. 5A to 5E.

FIG. 5A illustrates a television device 7100. In the television device7100, a display portion 7103 is incorporated in a housing 7101. Thedisplay portion 7103 is capable of displaying images, and alight-emitting device can be used for the display portion 7103. Inaddition, here, the housing 7101 is supported by a stand 7105.

The television device 7100 can be operated by an operation switch of thehousing 7101 or a separate remote controller 7110. With operation keys7109 of the remote controller 7110, channels and volume can becontrolled and images displayed on the display portion 7103 can becontrolled. The remote controller 7110 may be provided with a displayportion 7107 for displaying data output from the remote controller 7110.

Note that the television device 7100 is provided with a receiver, amodem, and the like. With the receiver, a general television broadcastcan be received. Furthermore, when the television device 7100 isconnected to a communication network by wired or wireless connection viathe modem, one-way (from a transmitter to a receiver) or two-way(between a transmitter and a receiver, between receivers, or the like)data communication can be performed.

FIG. 5B illustrates a computer, which includes a main body 7201, ahousing 7202, a display portion 7203, a keyboard 7204, an externalconnecting port 7205, a pointing device 7206, and the like. Thiscomputer is manufactured by using a light-emitting device for thedisplay portion 7203.

FIG. 5C illustrates a portable game machine having two housings, ahousing 7301 and a housing 7302, which are connected with a jointportion 7303 so that the portable game machine can be opened or folded.A display portion 7304 is incorporated in the housing 7301 and a displayportion 7305 is incorporated in the housing 7302. In addition, theportable game machine illustrated in FIG. 5C includes a speaker portion7306, a recording medium insertion portion 7307, an LED lamp 7308, aninput means (an operation key 7309, a connection terminal 7310, a sensor7311 (a sensor having a function of measuring force, displacement,position, speed, acceleration, angular velocity, rotational frequency,distance, light, liquid, magnetism, temperature, chemical substance,sound, time, hardness, electric field, current, voltage, electric power,radiation, flow rate, humidity, gradient, oscillation, smell, orinfrared rays), or a microphone 7312), and the like. Needless to say,the structure of the portable game machine is not limited to the aboveas long as a light-emitting device can be used for at least either thedisplay portion 7304 or the display portion 7305, or both, and mayinclude other accessories as appropriate. The portable game machineillustrated in FIG. 5C has a function of reading out a program or datastored in a storage medium to display it on the display portion, and afunction of sharing information with another portable game machine bywireless communication. The portable game machine illustrated in FIG. 5Ccan have a variety of functions without limitation to the above.

FIG. 5D illustrates an example of a mobile phone. A mobile phone 7400 isprovided with a display portion 7402 incorporated in a housing 7401,operation buttons 7403, an external connection port 7404, a speaker7405, a microphone 7406, and the like. Note that the mobile phone 7400is manufactured using a light-emitting device for the display portion7402.

When the display portion 7402 of the mobile phone 7400 illustrated inFIG. 5D is touched with a finger or the like, data can be input into thecellular phone 7400. Users can make calls and compose e-mails bytouching the display portion 7402 with a finger or the like.

There are mainly three screen modes of the display portion 7402. Thefirst mode is a display mode mainly for displaying images. The secondmode is an input mode mainly for inputting data such as text. The thirdmode is a display-and-input mode in which two modes of the display modeand the input mode are combined.

For example, in the case of making a call or composing an e-mail, a textinput mode mainly for inputting text is selected for the display portion7402 so that text displayed on a screen can be input. In this case, akeyboard or number buttons are preferably displayed on almost the entirescreen of the display portion 7402.

When a detection device including a sensor for detecting inclination,such as a gyroscope or an acceleration sensor, is provided inside themobile phone 7400, display on the screen of the display portion 7402 canbe automatically changed by determining the orientation of the mobilephone 7400 (whether the mobile phone is placed horizontally orvertically for a landscape mode or a portrait mode).

The screen modes are switched by touch on the display portion 7402 oroperation with the operation buttons 7403 of the housing 7401.Alternatively, the screen modes can be switched depending on the kind ofimage displayed on the display portion 7402. For example, when a signalof an image displayed on the display portion is a signal of moving imagedata, the screen mode is switched to the display mode. When the signalis a signal of text data, the screen mode is switched to the input mode.

Moreover, in the input mode, if a signal detected by an optical sensorin the display portion 7402 is detected and the input by touch on thedisplay portion 7402 is not performed for a certain period, the screenmode may be controlled so as to be switched from the input mode to thedisplay mode.

The display portion 7402 may function as an image sensor. For example,an image of a palm print, a fingerprint, or the like is taken by touchon the display portion 7402 with the palm or the finger, wherebypersonal authentication can be performed. Moreover, when a backlight ora sensing light source which emits near-infrared light is provided inthe display portion, an image of finger veins, palm veins, or the likecan be taken.

FIG. 5E illustrates a desk lamp, which includes a lighting portion 7501,a shade 7502, an adjustable arm 7503, a support 7504, a base 7505, and apower supply 7506. The desk lamp is manufactured using a light-emittingdevice for the lighting portion 7501. Note that a lamp includes aceiling light, a wall light, and the like in its category.

FIG. 6 illustrates an example in which a light-emitting device is usedfor an interior lighting device 801. Since the light-emitting device canhave a larger area, it can be used as a lighting device having a largearea. The light-emitting device can also be used as a roll-type lightingdevice 802. As illustrated in FIG. 6, a desk lamp 803 described withreference to FIG. 5E may also be used in a room provided with theinterior lighting device 801.

In the above manner, electronic devices and lighting devices can bemanufactured with the use of the light-emitting device. Applicationrange of the light-emitting device is so wide that the light-emittingdevice can be used for electronic devices in a variety of fields.

Note that the structure described in this embodiment can be combinedwith any of the structures described in Embodiments 1 to 4 asappropriate.

Example 1

In this example, Synthesis Example 1 and Synthesis Example 2 in each ofwhich 3-[4-(1-naphthyl)-phenyl]-9-phenyl-9H-carbazole (abbreviation:PCPN) represented by Structural Formula (100) in Embodiment 1 ismanufactured will be described.

Synthesis Example 1

In a 200-mL three-neck flask, a mixture of 5.0 g (15.5 mmol) of3-bromo-9-phenyl-9H-carbazole, 4.2 g (17.1 mmol) of4-(1-naphthyl)-phenylboronic acid, 38.4 mg (0.2 mmol) of palladium(II)acetate, 104 mg (0.3 mmol) of tris(2-methylphenyl)phosphine, 50 mL oftoluene, 5 mL of ethanol, and 30 mL of a potassium carbonate aqueoussolution (2 mol/L) was deaerated while being stirred under reducedpressure, and then heated and stirred in a nitrogen atmosphere at 85° C.for 9 hours to be reacted.

After the reaction, 500 mL of toluene was added to the reaction mixturesolution, and an organic layer of the mixture solution was filtratedthrough Florisil (Catalog No. 540-00135, produced by Wako Pure ChemicalIndustries, Ltd.), alumina (neutral, produced by Merck Ltd), and Celite(Catalog No. 531-16855, produced by Wako Pure Chemical Industries,Ltd.). The obtained filtrate was washed with water, and magnesiumsulfate was added thereto so that moisture was adsorbed. This suspensionwas filtrated to obtain a filtrate. The obtained filtrate wasconcentrated and purified by silica gel column chromatography. At thistime, a mixed solvent of toluene and hexane (toluene: hexane=1:4) wasused as a developing solvent for the chromatography. The obtainedfraction was concentrated, and methanol was added thereto. The mixturewas irradiated with ultrasonic waves and then recrystallized to give6.24 g of white powder that was an objective substance in a yield of90%. The reaction scheme of Synthesis Example 1 above is shown in(F1-1).

The Rf values of the objective substance and3-bromo-9-phenyl-9H-carbazole were respectively 0.42 and 0.58, whichwere obtained by silica gel thin layer chromatography (TLC) (with adeveloping solvent of ethyl acetate and hexane in a 1:10 ratio).

The compound obtained in Synthesis Example 1 was examined by a nuclearmagnetic resonance (NMR) method. The measurement data are shown below.

¹H NMR (CDCl₃, 300 MHz): δ (ppm)=7.30-7.35 (m, 1H), 7.44-7.67 (m, 14H),7.76 (dd, J=8.7 Hz, 1.8 Hz, 1H), 7.84-7.95 (m, 4H), 8.04 (d, J=7.8, 1H),8.23 (d, J=7.8, 1H), 8.46 (d, J=1.5, 1H).

FIGS. 7A and 7B are ¹H NMR charts. Note that FIG. 7B is a chart showingan enlarged part of FIG. 7A in the range of 7.0 ppm to 9.0 ppm. Themeasurement results confirmed that3-[4-(1-naphthyl)-phenyl]-9-phenyl-9H-carbazole (abbreviation: PCPN)that was the objective substance was able to be obtained.

Synthesis Example 2

In this synthesis example, a synthesis example of PCPN, which isdifferent from Synthesis Example 1, will be described.

Step 1: Synthesis Method of 3-(4-bromophenyl)-9-phenyl-9H-carbazole

In a 300-mL three-neck flask, a mixture of 14 g (50 mmol) of4-bromoiodobenzene, 14 g (50 mmol) of 9-phenyl-9H-carbazol-3-boronicacid, 110 mg (0.5 mmol) of palladium(II) acetate, 300 mg (1.0 mmol) oftri(o-tolyl)phosphine, 50 mL of toluene, 10 mL of ethanol, and 25 mL ofa potassium carbonate aqueous solution (2 mol/L) was deaerated whilebeing stirred under reduced pressure, and then heated and stirred in anitrogen atmosphere at 80° C. for 6 hours to be reacted.

After the reaction, 200 mL of toluene was added to the reaction mixturesolution, and the resulting suspension was filtrated through Florisiland Celite. The obtained filtrate was washed with water, and magnesiumsulfate was added thereto to adsorb moisture. This suspension wasfiltrated to obtain a filtrate. The obtained filtrate was concentratedand purified by silica gel column chromatography. At this time, a mixedsolvent of toluene and hexane (toluene: hexane=1:4) was used as adeveloping solvent for the chromatography. The obtained fraction wasconcentrated, and hexane was added thereto. The mixture was irradiatedwith ultrasonic waves and then recrystallized to give 15 g of whitepowder that was an objective substance in a yield of 75%. The reactionscheme of Step 1 above is shown in (F1-2).

The Rf values of the objective substance and 4-bromoiodobenzene wererespectively 0.32 and 0.74, which were obtained by silica gel thin layerchromatography (TLC) (with a developing solvent containing ethyl acetateand hexane in a 1:10 ratio).

The compound obtained in Step 1 was examined by a nuclear magneticresonance (NMR) method. The measurement data are shown below.

¹H NMR (CDCl₃, 300 MHz): δ (ppm)=7.24-7.32 (m, 1H), 7.40-7.64 (m, 13H),8.17 (d, J=7.2 Hz, 1H), 8.29 (s, 1H).

FIGS. 8A and 8B are ¹H NMR charts. Note that FIG. 8B is a chart showingan enlarged part of FIG. 8A in the range of 7.0 ppm to 8.5 ppm. Themeasurement results confirmed that3-(4-bromophenyl)-9-phenyl-9H-carbazole that was the objective substancewas able to be obtained.

The molecular weight of the above compound was measured with a GC-MSdetector (ITQ1100 ion trap GC/MS system, produced by Thermo FisherScientific K.K.). FIG. 9 is a chart thereof. The measurement detected amain peak at a molecular weight of 397.13 (the mode was EI+). Themeasurement results confirmed that3-(4-bromophenyl)-9-phenyl-9H-carbazole that was the objective substancewas able to be obtained.

Step 2: Synthesis Method of3-[4-(1-naphthyl)-phenyl]-9-phenyl-9H-carbazole (abbreviation: PCPN)

In a 50-mL three-neck flask, a mixture of 2.4 g (5.0 mmol) of3-(4-bromophenyl)-9-phenyl-9H-carbazole, 1.1 g (5.5 mmol) ofnaphthalene-1-boronic acid, 20 mg (0.1 mmol) of palladium(II) acetate,36 mg (0.1 mmol) of tri(o-tolyl)phosphine, 10 mL of toluene, 1.5 mL ofethanol, and 5 mL of a potassium carbonate aqueous solution (2 mol/L)was deaerated while being stirred under reduced pressure and was heatedand stirred in a nitrogen atmosphere at 90° C. for 14 hours to bereacted.

After the reaction, 200 mL of toluene was added to the reaction mixturesolution, and an organic layer of the mixture solution was filtratedthrough Florisil, alumina, and Celite. The obtained filtrate was washedwith water, and magnesium sulfate was added thereto so that moisture wasadsorbed. This suspension was filtrated to obtain a filtrate. Theobtained filtrate was concentrated and purified by silica gel columnchromatography. At this time, a mixed solvent of toluene and hexane(toluene: hexane=1:4) was used as a developing solvent for thechromatography. The obtained fraction was concentrated, and acetone andmethanol were added thereto. The mixture was irradiated with ultrasonicwaves and then recrystallized to give 2.3 g of white powder that was anobjective substance in a yield of 86%. The reaction scheme of Step 2 isshown in (F1-3).

The Rf values of the objective substance and3-(4-bromophenyl)-9-phenyl-9H-carbazole were respectively 0.57 and 0.65,which were obtained by silica gel thin layer chromatography (TLC) (witha developing solvent containing ethyl acetate and hexane in a 1:10ratio).

Further, the nuclear magnetic resonance (NMR) confirmed that thecompound obtained in Synthesis Example 2 was3-[4-(1-naphthyl)-phenyl]-9-phenyl-9H-carbazole (abbreviation: PCPN)that was an objective substance.

FIG. 10A shows an absorption spectrum of PCPN in a toluene solution ofPCPN, and FIG. 10B shows an emission spectrum thereof. FIG. 11A shows anabsorption spectrum of a thin film of PCPN, and FIG. 11B shows anemission spectrum thereof. The absorption spectrum was measured with anultraviolet-visible spectrophotometer (V550, produced by JASCOCorporation). The emission spectrum was measured with a fluorescencespectrophotometer (FS920, produced by Hamamatsu Photonics Corporation).The measurements were performed with samples prepared in such a mannerthat the solution was put in a quartz cell while the thin film wasobtained by evaporation onto a quartz substrate. FIG. 10A show theabsorption spectrum of PCPN in the solution of PCPN which was obtainedby subtracting the absorption spectra of the quartz cell and toluene puttherein. FIG. 11A shows the absorption spectrum of the thin film whichwas obtained by subtracting the absorption spectrum of the quartzsubstrate. In FIGS. 10A and 10B and FIGS. 11A and 11B, the horizontalaxis represents wavelength (nm) and the vertical axis representsintensity (arbitrary unit). In the case of the toluene solution, theabsorption peak was observed at around 300 nm, and the maximum emissionwavelength was 384 nm (excitation wavelength: 320 nm). In the case ofthe thin film, the absorption peak was observed at around 322 nm, andthe maximum emission wavelength was 398 nm (excitation wavelength: 324nm).

The absorption spectrum shows that PCPN described in this example is amaterial having weak absorption of light in the visible region. Inaddition, the emission spectrum shows that PCPN exhibits blue-violetemission.

Example 2

In this example, an example in which3-[4-(9-phenanthryl)-phenyl]-9-phenyl-9H-carbazole (abbreviation: PCPPn)represented by Structural Formula (102) in Embodiment 1 is manufacturedwill be described.

Step 1: Synthesis Method of 4-(9-phenyl-9H-carbazol-3-yl)phenylboronicacid

Into a 300-mL three-neck flask was put 8.0 g (20 mmol) of the3-(4-bromophenyl)-9-phenyl-9H-carbazole obtained in Reaction Scheme(F1-2), the atmosphere in the flask was replaced with nitrogen, 100 mLof dehydrated tetrahydrofuran (abbreviation: THF) was then added to theflask, and the temperature was lowered to −78° C. To this mixture, 3.4mL (30 mmol) of trimethyl borate was added, and the mixture with thetrimethyl borate added was stirred at −78° C. for 2 hours and at roomtemperature for 18 hours. After the reaction, 1M diluted hydrochloricacid was added to this reaction solution until the solution became acid,and the solution with the diluted hydrochloric acid added was stirredfor 7 hours. This solution was subjected to ethyl acetate extraction,and an organic layer obtained was washed with a saturated saline. Afterthe washing, magnesium sulfate was added to the organic layer to removemoisture. This suspension was filtrated, and the obtained filtrate wasconcentrated, and hexane was added thereto. The mixture was irradiatedwith ultrasonic waves and then recrystallized to give 6.4 g of whitepowder that was an objective substance in a yield of 88%. The reactionscheme of Step 1 is shown (F2-1).

The Rf values of the objective substance and3-(4-bromophenyl)-9-phenyl-9H-carbazole were respectively 0 (origin) and0.53, which were obtained by silica gel thin layer chromatography (TLC)(with a developing solvent containing ethyl acetate and hexane in a 1:10ratio). In addition, the Rf values of the objective substance and3-(4-bromophenyl)-9-phenyl-9H-carbazole were respectively 0.72 and 0.93,which were obtained by silica gel thin layer chromatography (TLC) usingethyl acetate as the developing solvent.

Step 2: Synthesis Method of3-[4-(9-phenanthryl)-phenyl]-9-phenyl-9H-carbazole (abbreviation: PCPPn)

In a 200-mL three-neck flask, a mixture of 1.5 g (5.0 mmol) of9-phenyl-9H-carbazole-3-yl-phenyl-4-boronic acid, 3.2 g (11 mmol) of9-bromophenanthrene, 11 mg (0.1 mmol) of palladium(II) acetate, 30 mg(0.1 mmol) of tri(o-tolyl)phosphine, 30 mL of toluene, 3 mL of ethanol,and 5 mL of a potassium carbonate aqueous solution (2 mol/L) wasdeaerated while being stirred under reduced pressure, and then heatedand stirred in a nitrogen atmosphere at 90° C. for 6 hours to bereacted.

After the reaction, 200 mL of toluene was added to the reaction mixturesolution, and an organic layer of the mixture solution was filtratedthrough Florisil, alumina, and Celite. The obtained filtrate was washedwith water, and magnesium sulfate was added thereto so that moisture wasadsorbed. This suspension was filtrated to obtain a filtrate. Theobtained filtrate was concentrated and purified by silica gel columnchromatography. At this time, a mixed solvent of toluene and hexane(toluene: hexane=1:4) was used as a developing solvent for thechromatography. The obtained fraction was concentrated, and acetone andmethanol were added thereto. The mixture was irradiated with ultrasonicwaves and then recrystallized to give 2.2 g of white powder that was anobjective substance in a yield of 75%. The reaction scheme of Step 2 isshown in (F2-2).

The Rf values of the objective substance and 9-bromophenanthrene wererespectively 0.33 and 0.70, which were obtained by silica gel thin layerchromatography (TLC) (with a developing solvent containing ethyl acetateand hexane in a 1:10 ratio).

The obtained compound was examined by a nuclear magnetic resonance (NMR)method. The measurement data are shown below.

¹H NMR (CDCl₃, 300 MHz): δ (ppm)=7.30-7.35 (m, 1H), 7.43-7.78 (m, 16H),7.86-7.93 (m, 3H), 8.01 (dd, J=0.9 Hz, 7.8 Hz, 1H), 8.23 (d, J=7.8 Hz,1H), 8.47 (d, J=1.5 Hz, 1H), 8.74 (d, J=8.1 Hz, 1H), 8.80 (d, J=7.8 Hz,1H).

FIGS. 12A and 12B are ¹H NMR charts. Note that FIG. 12B is a chartshowing an enlarged part of FIG. 12A in the range of 7.0 ppm to 9.0 ppm.The measurement results confirmed that PCPPn (abbreviation) that was theobjective substance was able to be obtained.

FIG. 13A shows an absorption spectrum of PCPPn in a toluene solution ofPCPPn, and FIG. 13B shows an emission spectrum thereof. FIG. 14A showsan absorption spectrum of a thin film of PCPPn, and FIG. 14A shows anemission spectrum thereof. The absorption spectrum was measured with anultraviolet-visible spectrophotometer (V550, produced by JASCOCorporation). The emission spectrum was measured with a fluorescencespectrophotometer (FS920, produced by Hamamatsu Photonics Corporation).The measurements were performed with samples prepared in such a mannerthat the solution was put in a quartz cell while the thin film wasobtained by evaporation onto a quartz substrate. FIG. 13A show theabsorption spectrum of PCPPn in the solution of PCPPn which was obtainedby subtracting the absorption spectra of the quartz cell and toluene puttherein, and FIG. 14A shows the absorption spectrum of the thin filmwhich was obtained by subtracting the absorption spectrum of the quartzsubstrate. In FIGS. 13A and 13B and FIGS. 14A and 14B, the horizontalaxis represents wavelength (nm) and the vertical axis representsintensity (arbitrary unit). In the case of the toluene solution, theabsorption peak was observed at around 300 nm, and the maximum emissionwavelength was 383 nm (excitation wavelength: 300 nm). In the case ofthe thin film, the absorption peak was observed at around 321 nm, andthe maximum emission wavelength was 410 nm (excitation wavelength: 331nm).

The absorption spectrum showed that PCPPn described in this example is amaterial having weak absorption of light in the visible region. Inaddition, the emission spectrum shows that PCPPn exhibits blue-violetemission.

Further, the glass transition temperature (Tg) of PCPPn was examinedwith a differential scanning calorimeter (DSC). The measurement resultshowed that the glass transition temperature is 114° C. In this manner,PCPPn has a high glass transition temperature and favorable heatresistance. In addition, the crystallization peak was not observed,which shows that PCPPn is a substance which is difficult to becrystallized.

Example 3

In this example, an example in which9-phenyl-3-[4-(triphenylen-2-yl)-phenyl]-9H-carbazole (abbreviation:PCzPTp) represented by Structural Formula (105) in Embodiment 1 ismanufactured will be described.

In a 100-mL three-neck flask, a mixture of 0.5 g (2.0 mmol) of2-bromotriphenylene, 3.3 g (9.2 mmol) of4-(9-phenyl-9H-carbazol-3-yl)phenylboronic acid, 20 mg (0.1 mmol) ofpalladium(II) acetate, 60 mg (0.2 mmol) of tri(o-tolyl)phosphine, 20 mLof toluene, 2 mL of ethanol, and 7.5 mL of a potassium carbonate aqueoussolution (2 mol/L) was deaerated while being stirred under reducedpressure, and then heated and stirred in a nitrogen atmosphere at 85° C.for 16 hours to be reacted.

After the reaction, 500 mL of toluene was added to the reaction mixturesolution, and an organic layer of the mixture solution was filtratedthrough Florisil, alumina, and Celite. The obtained filtrate was washedwith water, and magnesium sulfate was added thereto so that moisture wasadsorbed. This suspension was filtrated to obtain a filtrate. Theobtained filtrate was concentrated and purified by silica gel columnchromatography. At this time, toluene was used as a developing solventfor the chromatography. The obtained fraction was concentrated, andmethanol was added thereto. The mixture was irradiated with ultrasonicwaves and then recrystallized to give white powder that was an objectivesubstance. The reaction scheme of the synthesis method is shown in(F3-1).

The Rf values of the objective substance and 2-bromotriphenylene wererespectively 0.21 and 0.46, which were obtained by silica gel thin layerchromatography (TLC) (with a developing solvent containing ethyl acetateand hexane in a 1:10 ratio).

The obtained compound was examined by a nuclear magnetic resonance (NMR)method. The measurement data are shown below.

¹H NMR (CDCl₃, 300 MHz): δ (ppm)=7.31-7.36 (m, 1H), 7.45-7.53 (m, 4H),7.61-7.78 (m, 9H), 7.89-8.01 (m, 5H), 8.24 (d, J=7.5 Hz, 1H), 8.46 (d,J=1.5 Hz, 1H), 8.67-8.82 (m, 5H), 8.95 (d, J=2.1 Hz, 1H).

FIGS. 15A and 15B are ¹H NMR charts. Note that FIG. 15B is a chartshowing an enlarged part of FIG. 15A in the range of 7.0 ppm to 9.5 ppm.The measurement results confirmed that PCzPTp that was the objectivesubstance was able to be obtained.

FIG. 16A shows an absorption spectrum of PCzPTp in a toluene solution ofPCzPTp, and FIG. 16B shows an emission spectrum thereof. The absorptionspectrum was measured with an ultraviolet-visible spectrophotometer(V550, produced by JASCO Corporation). The emission spectrum wasmeasured with a fluorescence spectrophotometer (FS920, produced byHamamatsu Photonics Corporation). The measurements were performed insuch a manner that the solution was put in a quartz cell. FIG. 16A showthe absorption spectrum of PCzPTp in the solution of PCzPTp which wasobtained by subtracting the absorption spectra of the quartz cell andtoluene put therein. In FIGS. 16A and 16B, the horizontal axisrepresents wavelength (nm) and the vertical axis represents intensity(arbitrary unit). In the case of the toluene solution, the absorptionpeak was observed at around 325 nm, and the maximum emission wavelengthwas 385 nm (excitation wavelength: 347 nm).

The absorption spectrum showed that PCzPTp described in this example isa material having weak absorption of light in the visible region. Inaddition, the emission spectrum shows that PCzPTp exhibits blue-violetemission.

Example 4

In this example, an example in which3-[3-(9-phenanthryl)-phenyl]-9-phenyl-9H-carbazole (abbreviation:mPCPPn) represented by Structural Formula (108) in Embodiment 1 ismanufactured will be described.

Step 1: Synthesis Method of 3-(3-bromophenyl)-9-phenyl-9H-carbazole

In a 500-mL three-neck flask, a mixture of 31 g (110 mmol) of3-bromoiodobenzene, 29 g (100 mmol) of 9-phenyl-9H-carbazole-3-boronicacid, 22 mg (0.1 mmol) of palladium(II) acetate, 60 mg (1.2 mmol) oftri(o-tolyl)phosphine, 100 mL of toluene, 10 mL of ethanol, and 50 mL ofa potassium carbonate aqueous solution (2 mol/L) was deaerated whilebeing stirred under reduced pressure, and then heated and stirred in anitrogen atmosphere at 80° C. for 2.5 hours to be reacted.

After the reaction, 200 mL of toluene was added to the reaction mixturesolution, and the resulting suspension was filtrated through Florisiland Celite. The obtained filtrate was washed with water, and magnesiumsulfate was added thereto to adsorb moisture. This suspension wasfiltrated to obtain a filtrate. The obtained filtrate was concentrated,and toluene and methanol were added thereto. The mixture was irradiatedwith ultrasonic waves and then recrystallized to give 22 g of whitepowder that was an objective substance in a yield of 54%. The reactionscheme of Step 1 is shown in (F4-1).

The Rf values of the objective substance and 3-bromoiodobenzene wererespectively 0.29 and 0.67, which were obtained by silica gel thin layerchromatography (TLC) (with a developing solvent containing ethyl acetateand hexane in a 1:10 ratio).

Step 2: Synthesis Method of3-[3-(9-phenanthryl)-phenyl]-9-phenyl-9H-carbazole (abbreviation:mPCPPn)

In a 200-mL three-neck flask, a mixture of 3.0 g (7.5 mmol) of3-(3-bromophenyl)-9-phenyl-9H-carbazole, 1.8 g (8.29 mmol) ofphenanthrene-9-boronic acid, 19 mg (0.1 mmol) of palladium(II) acetate,76 mg (0.2 mmol) of tris(2-methylphenyl)phosphine, 70 mL of toluene, 7mL of ethanol, and 20 mL of a potassium carbonate aqueous solution (2mol/L) was deaerated while being stirred under reduced pressure, andthen heated and stirred in a nitrogen atmosphere at 100° C. for 5 hoursto be reacted.

After the reaction, 500 mL of toluene was added to the reaction mixturesolution, and an organic layer of the mixture solution was filtratedthrough Florisil, alumina, and Celite. The obtained filtrate was washedwith water, and magnesium sulfate was added thereto to adsorb moisture.This suspension was filtrated to obtain a filtrate. The obtainedfiltrate was concentrated and purified by silica gel columnchromatography. At this time, a mixed solvent of toluene and hexane(toluene: hexane=2:3) was used as a developing solvent for thechromatography. The obtained fraction was concentrated, and hexane wasadded thereto. The mixture was irradiated with ultrasonic waves and thenrecrystallized to give 2.76 g of white powder that was an objectivesubstance in a yield of 74%. The reaction scheme of Step 2 is shown in(F4-2).

The Rf values of the objective substance and3-(3-bromophenyl)-9-phenyl-9H-carbazole were respectively 0.25 and 0.58,which were obtained by silica gel thin layer chromatography (TLC) (witha developing solvent containing ethyl acetate and hexane in a 1:10ratio).

The obtained compound was examined by a nuclear magnetic resonance (NMR)method. The measurement data are shown below.

¹H NMR (CDCl₃, 300 MHz): δ (ppm)=7.28-7.32 (m, 1H), 7.42-7.76 (m, 15H),7.81-7.84 (m, 2H), 7.92-7.95 (m, 2H), 8.06 (d, J=8.1 Hz, 1H), 8.18 (d,J=7.8 Hz, 1H), 8.44 (d, J=1.5 Hz, 1H), 8.76 (d, J=8.1 Hz, 1H), 8.81 (d,J=8.7 Hz, 1H).

FIGS. 17A and 17B are ¹H NMR charts. Note that FIG. 17B is a chartshowing an enlarged part of FIG. 17A in the range of 6.5 ppm to 9.0 ppm.The measurement results confirmed that mPCPPn that was the objectivesubstance was able to be obtained.

FIG. 18A shows an absorption spectrum of mPCPPn, in a toluene solutionof mPCPPn, and FIG. 18B shows an emission spectrum thereof FIG. 19Ashows an absorption spectrum of a thin film of mPCPPn, and FIG. 19Bshows an emission spectrum thereof. The absorption spectrum was measuredwith an ultraviolet-visible spectrophotometer (V550, produced by JASCOCorporation). The emission spectrum was measured with a fluorescencespectrophotometer (FS920, produced by Hamamatsu Photonics Corporation).The measurements were performed with samples prepared in such a mannerthat the solution was put in a quartz cell while the thin film wasobtained by evaporation onto a quartz substrate. FIG. 18A show theabsorption spectrum of mPCPPn in the solution of mPCPPn which wasobtained by subtracting the absorption spectra of the quartz cell andtoluene put therein, and FIG. 19A shows the absorption spectrum of thethin film which was obtained by subtracting the absorption spectrum ofthe quartz substrate. In FIGS. 18A and 18B and FIGS. 19A and 19B, thehorizontal axis represents wavelength (nm) and the vertical axisrepresents intensity (arbitrary unit). In the case of the toluenesolution, the absorption peak was observed at around 298 nm, and themaximum emission wavelength was 363 nm (excitation wavelength: 311 nm).In the case of the thin film, the absorption peak was observed at around350 nm, and the maximum emission wavelength was 389 nm (excitationwavelength: 353 nm).

The absorption spectrum showed that mPCPPn described in this example isa material having weak absorption of light in the visible region. Inaddition, the emission spectrum shows that mPCPPn exhibits blue-violetemission.

Further, the glass transition temperature (Tg) of mPCPPn was examinedwith a differential scanning calorimeter (DSC). The measurement resultshowed that the glass transition temperature is 109° C. In this manner,mPCPPn has a high glass transition temperature and favorable heatresistance. In addition, the crystallization peak was not observed,which shows that mPCPPn is a substance which is difficult to becrystallized.

Example 5

In this example, an example in which9-phenyl-3-[3-(triphenylen-2-yl)-phenyl]-9H-carbazole (abbreviation:mPCzPTp) represented by Structural Formula (III) in Embodiment 1 ismanufactured will be described.

In a 50-mL three-neck flask, a mixture of 0.7 g (1.8 mmol) of3-bromo-9-phenyl-9H-carbazole, 0.5 g (1.8 mmol) oftriphenylene-2-boronic acid, 4.1 mg (18 μmol) of palladium(II) acetate,28 mg (92 μmol) of tri(o-tolyl)phosphine, 6.9 mL of toluene, 2.3 mL ofethanol, and 1.9 mL of a potassium carbonate aqueous solution (2 mol/L)was deaerated while being stirred under reduced pressure, and thenheated and stirred in a nitrogen atmosphere at 80° C. for 3 hours to bereacted.

After the reaction, an aqueous layer of the obtained suspension wasextracted with toluene. The obtained extracted solution and thesuspension were washed together with saturated saline, and thenmagnesium sulfate was added to the obtained solution so that moisturewas adsorbed. The suspension was separated by gravity filtration, andthe filtrate was concentrated to give an oily substance. This oilysubstance was purified by silica gel column chromatography. The columnchromatography was performed first using a mixed solvent of toluene andhexane (toluene: hexane=1:9) as a developing solvent, and then using amixed solvent of toluene and hexane (toluene: hexane=1:6) as adeveloping solvent. The obtained fractions were concentrated to give anoily substance. Toluene and hexane were added to the oily substance, andthe mixture was crystallized to give 0.9 g of a white solid that was anobjective substance in a yield of 90%. The reaction scheme of thesynthesis method is shown in (F5-1).

The obtained compound was examined by a nuclear magnetic resonance (NMR)method. The measurement data are shown below.

¹H NMR (CDCl₃, 300 MHz): δ (ppm)=7.30-7.54 (m, 5H), 7.60-7.80 (m, 12H),8.01 (dd, J=8.4 Hz, 1.5 Hz, 1H), 8.14 (s, 1H), 8.23 (d, J=7.8 Hz, 1H),8.47 (d, J=2.1 Hz, 1H), 8.67-8.80 (m, 5H), 8.95 (d, J=1.5 Hz, 1H).

FIGS. 20A and 20B are ¹H NMR charts. Note that FIG. 203 is a chartshowing an enlarged part of FIG. 20A in the range of 7.0 ppm to 9.0 ppm.The measurement results confirmed that mPCzPTp that was the objectivesubstance was able to be obtained.

FIG. 21A shows an absorption spectrum of mPCzPTp in a toluene solutionof mPCzPTp, and FIG. 21B shows an emission spectrum thereof FIG. 22Ashows an absorption spectrum of a thin film of mPCzPTp, and FIG. 22Bshows an emission spectrum thereof. The absorption spectrum was measuredwith a UV-visible spectrophotometer (V550, produced by JASCOCorporation). The emission spectrum was measured with a fluorescencespectrophotometer (FS920, produced by Hamamatsu Photonics Corporation).The measurements were performed with samples prepared in such a mannerthat the solution was put in a quartz cell while the thin film wasobtained by evaporation onto a quartz substrate. FIG. 21A show theabsorption spectrum of mPCzPTp in the solution of mPCzPTp which wasobtained by subtracting the absorption spectra of the quartz cell andtoluene put therein, and FIG. 22A shows the absorption spectrum of thethin film which was obtained by subtracting the absorption spectrum ofthe quartz substrate. In FIGS. 21A and 21B and FIGS. 22A and 22B, thehorizontal axis represents wavelength (nm) and the vertical axisrepresents intensity (arbitrary unit). In the case of the toluenesolution, the absorption peak was observed at around 290 nm, and themaximum emission wavelength was 381 nm (excitation wavelength: 290 nm).In the case of the thin film, the absorption peak was observed at around277 nm, and the maximum emission wavelength was 397 nm (excitationwavelength: 306 nm).

The absorption spectrum showed that mPCzPTp described in this example isa material having weak absorption of light in the visible region. Inaddition, the emission spectrum shows that mPCzPTp exhibits blue-violetemission.

Example 6

In this example, an example in which9-(1-naphthyl)-3-[4-(1-naphthyl)-phenyl]-9H-carbazole (abbreviation:NCPN) represented by Structural Formula (120) in Embodiment 1 ismanufactured will be described.

Step 1: Synthesis Method of 3-bromo-9-(1-naphthyl)-9H-carbazole

In a 200-mL conical flask, 5.9 g (20 mmol) of9-(1-naphthyl)-9H-carbazole was dissolved in a mixture solvent of 50 mLof toluene and 70 mL of ethyl acetate, and then 3.6 g (20 mmol) ofN-bromosuccinimide (abbreviation: NBS) was added to this solution. Themixture was stirred at room temperature for 36 hours. After completionof the reaction, this mixture solution was washed with water, andmagnesium sulfate was added thereto so that moisture was adsorbed. Thissuspension was filtrated, and the obtained filtrate was concentrated andcollected. As a result, 7.4 g of white powder that was an objectivesubstance was obtained in a yield of 99%. The synthesis scheme of Step 1is shown in (F6-1).

Step 2: Synthesis Method of9-(1-naphthyl)-3-[4-(1-naphthyl)-phenyl]-9H-carbazole (abbreviation:NCPN)

In a 200-mL three-neck flask, a mixture of 5.0 g (13 mmol) of3-bromo-9-(1-naphthyl)-9H-carbazole, 3.7 g (15 mmol) of4-(1-naphthyl)phenylboronic acid, 34 mg (0.2 mmol) of palladium(II)acetate, 91 mg (0.3 mmol) of tris(2-methylphenyl)phosphine, 50 mL oftoluene, 5 mL of ethanol, and 30 mL of a potassium carbonate aqueoussolution (2 mol/L) was deaerated while being stirred under reducedpressure, and then heated and stirred in a nitrogen atmosphere at 100°C. for 1 hour to be reacted. Furthermore, 334 mg (1.35 mmol) of4-(1-naphthyl)phenylboronic acid, 15.0 mg (0.07 mmol) of palladium(II)acetate, and 45 mg (0.15 mmol) of tris(2-methylphenyl)phosphine wereadded, and the mixture was heated and stirred in a nitrogen atmosphereat 100° C. for 6 hours to be reacted.

After the reaction, 500 mL of toluene was added to the reaction mixturesolution, and an organic layer of the mixture solution was filtratedthrough Florisil, alumina, and Celite. The obtained filtrate was washedwith water, and magnesium sulfate was added thereto to adsorb moisture.This suspension was filtrated to obtain a filtrate. The obtainedfiltrate was concentrated and purified by silica gel columnchromatography. At this time, a mixed solvent of toluene and hexane(toluene: hexane=1:4) was used as a developing solvent for thechromatography. The obtained fraction was concentrated, and hexane wasadded thereto. The mixture was irradiated with ultrasonic waves and thenrecrystallized to give 5.4 g of white powder that was an objectivesubstance in a yield of 82%. The reaction scheme of Step 2 is shown in(F6-2).

The Rf values of the objective substance and3-bromo-9-(1-naphthyl)-9H-carbazole were respectively 0.25 and 0.53which were obtained by silica gel thin layer chromatography (TLC) (witha developing solvent containing ethyl acetate and hexane in a 1:10ratio).

The obtained compound was examined by a nuclear magnetic resonance (NMR)method. The measurement data are shown below.

¹H NMR (CDCl₃, 300 MHz): δ (ppm)=7.04 (dd, J=6.3 Hz, 1.5 Hz, 1H), 7.11(d, J=8.4 Hz, 1H), 7.30-7.70 (m, 14H), 7.83-7.94 (m, 4H), 8.02-8.07 (m,3H), 8.28 (dd, J=6.3 Hz, 2.4 Hz, 1H), 8.52 (d, J=1.5 Hz, 1H).

FIGS. 23A and 23B are ¹H NMR charts. Note that FIG. 23B is a chartshowing an enlarged part of FIG. 23A in the range of 6.0 ppm to 9.0 ppm.The measurement results confirmed that NCPN that was the objectivesubstance was able to be obtained.

FIG. 24A shows an absorption spectrum of NCPN in a toluene solution ofNCPN, and FIG. 24B shows an emission spectrum thereof. FIG. 25A shows anabsorption spectrum of a thin film of NCPN, and FIG. 25B shows anemission spectrum thereof. The absorption spectrum was measured with aUV-visible spectrophotometer (V550, produced by JASCO Corporation). Theemission spectrum was measured with a fluorescence spectrophotometer(FS920, produced by Hamamatsu Photonics Corporation). The measurementswere performed with samples prepared in such a manner that the solutionwas put in a quartz cell while the thin film was obtained by evaporationonto a quartz substrate. FIG. 24A show the absorption spectrum of NCPNin the solution of NCPN which was obtained by subtracting the absorptionspectra of the quartz cell and toluene put therein, and FIG. 25A showsthe absorption spectrum of the thin film which was obtained bysubtracting the absorption spectrum of the quartz substrate. In FIGS.24A and 24B and FIGS. 25A and 25B, the horizontal axis representswavelength (nm) and the vertical axis represents intensity (arbitraryunit). In the case of the toluene solution, the absorption peak wasobserved at around 300 nm, and the maximum emission wavelength was 388nm (excitation wavelength: 300 nm). In the case of the thin film, theabsorption peak was observed at around 322 nm, and the maximum emissionwavelength was 397 nm (excitation wavelength: 328 nm).

The absorption spectrum showed that NCPN described in this example is amaterial having weak absorption of light in the visible region. Inaddition, the emission spectrum shows that NCPN exhibits blue-violetemission.

Example 7

In this example, an example in which3,6-bis-[4-(1-naphthyl)-phenyl]-9-phenyl-9H-carbazole (abbreviation:NP2PC) represented by Structural Formula (112) in Embodiment 1 ismanufactured will be described.

In a 200-mL three-neck flask, a mixture of 2.0 g (5.0 mmol) of3,6-dibromo-9-phenyl-9H-carbazole, 2.7 g (11 mmol) of4-(1-naphthyl)phenylboronic acid, 100 mg (0.5 mmol) of palladium(II)acetate, 41 mg (0.1 mmol) of tri(o-tolyl)phosphine, 20 mL of toluene, 2mL of ethanol, and 30 mL of a potassium carbonate aqueous solution (2mol/L) was deaerated while being stirred under reduced pressure, andthen heated and stirred in a nitrogen atmosphere at 85° C. for 13 hoursto be reacted.

After the reaction, 150 mL of toluene was added to the reaction mixturesolution, and an organic layer of the mixture solution was filtratedthrough Florisil, alumina, and Celite. The obtained filtrate was washedwith water, and magnesium sulfate was added thereto to adsorb moisture.This suspension was filtrated to obtain a filtrate. The obtainedfiltrate was concentrated and purified by silica gel columnchromatography. At this time, a mixed solvent of toluene and hexane(toluene: hexane=1:4) was used as a developing solvent for thechromatography. The obtained fraction was concentrated, and acetone andmethanol were added thereto. The mixture was irradiated with ultrasonicwaves and then recrystallized to give 2.2 g of white powder that was anobjective substance in a yield of 69%. The reaction scheme of thesynthesis method is shown in (F7-1).

The Rf values of the objective substance and3,6-dibromo-9-phenyl-9H-carbazole were respectively 0.25 and 0.58 whichwere obtained by silica gel thin layer chromatography (TLC) (with adeveloping solvent containing ethyl acetate and hexane in a 1:10 ratio).

The obtained compound was examined by a nuclear magnetic resonance (NMR)method. The measurement data are shown below.

¹H NMR (CDCl₃, 300 MHz): δ (ppm)=7.45-7.68 (m, 19H), 8.02 (dd, J=2.1 Hz,9.0 Hz, 2H), 7.87-7.95 (m, 8H), 8.05 (d, J=7.8 Hz, 2H), 8.55 (d, J=1.5Hz, 2H).

FIGS. 26A and 26B are ¹H NMR charts. Note that FIG. 26B is a chartshowing an enlarged part of FIG. 26A in the range of 7.0 ppm to 9.0 ppm.The measurement results confirmed that NP2PC that was the objectivesubstance was able to be obtained.

FIG. 27A shows an absorption spectrum of NP2PC in a toluene solution ofNP2PC, and FIG. 27B shows an emission spectrum thereof. FIG. 28A showsan absorption spectrum of a thin film of NP2PC, and FIG. 28B shows anemission spectrum thereof. The absorption spectrum was measured with aUV-visible spectrophotometer (V550, produced by JASCO Corporation). Theemission spectrum was measured with a fluorescence spectrophotometer(FS920, produced by Hamamatsu Photonics Corporation). The measurementswere performed with samples prepared in such a manner that the solutionwas put in a quartz cell while the thin film was obtained by evaporationonto a quartz substrate. FIG. 27A show the absorption spectrum of NP2PCin the solution of NP2PC which was obtained by subtracting theabsorption spectra of the quartz cell and toluene put therein, and FIG.28A shows the absorption spectrum of the thin film which was obtained bysubtracting the absorption spectrum of the quartz substrate. In FIGS.27A and 27B and FIGS. 28A and 28B, the horizontal axis representswavelength (nm) and the vertical axis represents intensity (arbitraryunit). In the case of the toluene solution, the absorption peak wasobserved at around 314 nm, and the maximum emission wavelength was 392nm (excitation wavelength: 310 nm). In the case of the thin film, theabsorption peak was observed at around 314 nm, and the maximum emissionwavelength was 404 nm (excitation wavelength: 315 nm).

The absorption spectrum showed that NP2PC described in this example is amaterial having weak absorption of light in the visible region. Inaddition, the emission spectrum shows that NP2PC exhibits blue-violetemission.

Further, the thermophysical property was examined with a differentialscanning calorimeter (DSC). The measurement result showed that themelting point is 269° C. In addition, glass transition and acrystallization peak were not observed; thus, it was found that NP2PC isa substance which is difficult to be crystallized.

Example 8

In this example, measurement results of the highest occupied molecularorbital (HOMO) level, the lowest unoccupied molecular orbital (LUMO)level, and the band gap (Bg) of each of the carbazole compoundsaccording to one embodiment of the invention which were synthesized inExamples 1, 2, and 4 to 7, in a thin film state, will be described.

Note that the measurement in this example was performed as describedbelow. The value of the HOMO level was obtained by conversion of a valueof the ionization potential measured with a photoelectron spectrometer(AC-2, manufactured by Riken Keiki Co., Ltd.) in the air into a negativevalue. The value of the LUMO level was obtained in such a manner thatthe absorption edge, which is obtained from Tauc plot with an assumptionof direct transition, using data on the absorption spectrum of the thinfilm described in each Example, is regarded as an optical energy gap andis added to the value of the HOMO level.

Table 1 shows the HOMO levels and the LUMO levels of PCPN, PCPPn,mPCPPn, mPCzPTp, NCPN, and NP2PC which were obtained by the measurement.

TABLE 1 Abbreviation HOMO level LUMO level Band gap PCPN −5.77 −2.293.48 PCPPn −5.78 −2.25 3.53 mPCPPn −5.69 −2.37 3.32 mPCzPTp −5.70 −2.413.29 NCPN −5.83 −2.37 3.46 NP2PC −5.74 −2.36 3.38

Table 1 confirms that PCPN, PCPPn, mPCPPn, mPCzPTp, NCPN, and NP2PC eachof which is the carbazole compound according to one embodiment of thepresent invention have relatively deep HOMO levels, shallow LUMO levels,and wide band gaps.

Example 9

In this example, manufacturing methods of light-emitting elements eachof which is one embodiment of the present invention and measurementresults of the element characteristics will be described together withmeasurement results of a comparative light-emitting element.

Manufacturing methods of a light-emitting element 1, a light-emittingelement 2, and a comparative light-emitting element 1 will be describedbelow with reference to FIG. 29. In addition, structural formulae oforganic compounds used in this example are shown below.

(Light-Emitting Element 1)

First, indium tin oxide containing silicon oxide (ITSO) was deposited bya sputtering method on a glass substrate 1100, so that a first electrode1101 was formed. The thickness of the first electrode 1101 was 110 nm.The electrode area was 2 mm×2 mm. In this example, the first electrode1101 was used as an anode.

Next, the substrate 1100 provided with the first electrode 1101 wasfixed to a substrate holder in a vacuum evaporation apparatus so that asurface on which the first electrode 1101 was provided faced downward.The pressure in the vacuum evaporation apparatus was reduced to about10⁻⁴ Pa. After that, 3-[4-(1-naphthyl)-phenyl]-9-phenyl-9H-carbazole(abbreviation: PCPN) synthesized in Example 1 and molybdenum(VI) oxidewere co-evaporated to form a hole-injection layer 1111 on the firstelectrode 1101. The thickness of the hole-injection layer 1111 was 50nm. The weight ratio of PCPN to molybdenum(VI) oxide was adjusted to be4:2 (=PCPN: molybdenum oxide). Note that the co-evaporation methodrefers to an evaporation method in which evaporation is carried out froma plurality of evaporation sources at the same time in one treatmentchamber.

Next, PCPN was deposited to a thickness of 10 nm on the hole-injectionlayer 1111 to form a hole-transport layer 1112.

Furthermore, 9-[4-(N-carbazolyl)phenyl]-10-phenylanthracene(abbreviation: CzPA) andN,N′-bis[4-(9-phenyl-9H-fluoren-9-yl)phenyl]-N,N′-diphenylpyrene-1,6-diamine(abbreviation: 1,6FLPAPrn) were co-evaporated to form a light-emittinglayer 1113 on the hole-transport layer 1112. The weight ratio of CzPA to1,6FLPAPrn was adjusted to 1:0.05 (=CzPA: 1,6FLPAPrn). The thickness ofthe light-emitting layer 1113 was 30 nm.

Next, CzPA was deposited to a thickness of 10 nm on the light-emittinglayer 1113 to form a first electron-transport layer 1114 a.

After that, bathophenanthroline (abbreviation: BPhen) was deposited to athickness of 15 nm on the first electron-transport layer 1114 a to forma second electron-transport layer 1114 b.

Furthermore, a lithium fluoride (LiF) film was formed to a thickness of1 nm on the second electron-transport layer 1114 b by evaporation toform an electron-injection layer 1115.

Lastly, a 200-nm-thick film of aluminum was formed by evaporation toform a second electrode 1103 functioning as a cathode. Thus, thelight-emitting element 1 of this example was manufactured.

Note that, in the above evaporation process, evaporation was allperformed by a resistance heating method.

(Light-Emitting Element 2)

The light-emitting element 2 was formed in a manner similar to that ofthe light-emitting element 1 except for the hole-injection layer 1111and the hole-transport layer 1112.

In the light-emitting element 2, the hole-injection layer 1111 wasformed in such a manner that3-[4-(9-phenanthryl)-phenyl]-9-phenyl-9H-carbazole (abbreviation: PCPPn)synthesized in Example 2 and molybdenum(VI) oxide were co-evaporated onthe first electrode 1101. The thickness of the hole-injection layer 1111was 50 nm. The weight ratio of PCPPn to molybdenum(VI) oxide wasadjusted to 4:2 (=PCPPn: molybdenum oxide).

Next, PCPPn was deposited to a thickness of 10 nm on the hole-injectionlayer 1111 to form the hole-transport layer 1112.

(Comparative Light-Emitting Element 1)

The comparative light-emitting element 1 was formed in a manner similarto that of the light-emitting element 1 except for the hole-injectionlayer 1111 and the hole-transport layer 1112.

In the comparative light-emitting element 1, the hole-injection layer1111 was formed in such a manner that9-[4-(9-phenylcarbazol-3-yl)phenyl]-10-phenylanthracene (abbreviation:PCzPA) and molybdenum(VI) oxide were co-evaporated on the firstelectrode 1101. The thickness of the hole-injection layer 1111 was 50nm. The weight ratio of PCzPA to molybdenum(VI) oxide was adjusted to be4:2 (=PCzPA: molybdenum oxide).

Next, PCzPA was deposited to a thickness of 10 nm on the hole-injectionlayer 1111 to form the hole-transport layer 1112.

Table 2 shows the element structures of the light-emitting element 1,the light-emitting element 2, and the comparative light-emitting element1 that were manufactured as described above.

TABLE 2 Light-Emitting Light-Emitting Comparative Light- Element 1Element 2 Emitting Element 1 First Electrode ITSO ITSO ITSO 1101 110 nm 110 nm  110 nm  Hole-injection Layer PCPN:MoOx PCPPn:MoOx PCzPA:MoOx1111 (=4:2) (=4:2) (=4:2) 50 nm 50 nm 50 nm Hole-transport layer PCPNPCPPn PCzPA 1112 10 nm 10 nm 10 nm Light-emitting layer CzPA: CzPA:CzPA: 1113 1,6FLPAPrn 1,6FLPAPrn 1,6FLPAPrn (=1:0.05) (=1:0.05)(=1:0.05) 30 nm 30 nm 30 nm Electron-transport 1114a CzPA CzPA CzPAlayer 10 nm 10 nm 10 nm 1114b BPhen BPhen BPhen 15 nm 15 nm 15 nmElectron-injection layer LiF LiF LiF 1115  1 nm  1 nm  1 nm SecondElectrode Al Al Al 1103 200 nm  200 nm  200 nm  *The mixture ratios areall represented in weight ratios.

In a glove box containing a nitrogen atmosphere, the light-emittingelement 1, the light-emitting element 2, and the comparativelight-emitting element 1 were sealed so as not to be exposed to the air.After that, the operating characteristics of these elements weremeasured. Note that the measurement was carried out at room temperature(in an atmosphere kept at 25° C.).

Note that the light-emitting element 1, the light-emitting element 2,and the comparative light-emitting element 1 were formed over the samesubstrate. In addition, in the above three light-emitting elements, therespective components other than the hole-injection layers and thehole-transport layers were formed at the same time, and the operatingcharacteristics of the three light-emitting elements were measured atthe same time.

Table 3 shows the voltage (V), current density (mA/cm²), CIEchromaticity coordinates (x,y), luminance (cd/m²), current efficiency(cd/A), power efficiency (lm/W), and external quantum efficiency (%) ofeach of the light-emitting element 1, the light-emitting element 2, andthe comparative light-emitting element 1 at a luminance of about 1000cd/m².

TABLE 3 Light-Emitting Light-Emitting Comparative Light- Element 1Element 2 Emitting Element 1 Voltage (V) 3.0 3.0 3.0 Current density(mA/cm²) 9.3 7.5 8.3 Chromaticity coordinates (0.15, 0.21) (0.15, 0.21)(0.14, 0.20) (x, y) Luminance (cd/m²) 930 770 650 Current efficiency(cd/A) 10 10 8.0 Power efficiency (lm/W) 10 11 8.0 External quantum 6.86.9 5.6 efficiency (%)

FIG. 30 shows the emission spectra of the light-emitting element 1, thelight-emitting element 2, and the comparative light-emitting element 1.In FIG. 30, the horizontal axis represents the wavelength (nm) and thevertical axis represents the emission intensity (arbitrary unit). FIG.31, FIG. 32, and FIG. 33 respectively show the voltage-luminancecharacteristics, the luminance-current efficiency characteristics, andthe luminance-power efficiency characteristics of the light-emittingelement 1, the light-emitting element 2, and the comparativelight-emitting element 1. In FIG. 31, the vertical axis represents theluminance (cd/m²) and the horizontal axis represents the voltage (V). InFIG. 32, the vertical axis represents the current efficiency (cd/A) andthe horizontal axis represents the luminance (cd/m²). In FIG. 33, thevertical axis represents the power efficiency (lm/W) and the horizontalaxis represents the luminance (cd/m²).

According to FIG. 30, all of the emission spectra of the light-emittingelement 1, the light-emitting element 2, and the comparativelight-emitting element 1 have peaks around 470 nm. The CIE chromaticitycoordinates in Table 3 also show that the light-emitting element 1, thelight-emitting element 2, and the comparative light-emitting element 1exhibit blue light emission originating from 1,6FLPAPrn and that all theelements have excellent carrier balance.

Further, FIGS. 31 to 33 and Table 3 show that the light-emitting element1 and the light-emitting element 2 can be driven at a voltage as low asthat of the comparative light-emitting element 1 and that thelight-emitting element 1 and the light-emitting element 2 have higherefficiency than the comparative light-emitting element 1.

The reason for the above is probably as follows. The band gap of PCzPAused in the comparative light-emitting element 1 is 2.92 eV, and energytransfer from the light-emitting layer (transfer of excitons generatedin the light-emitting layer) occurs when PCzPA is used for thehole-transport layer in contact with the light-emitting layer; incontrast, the band gaps of PCPN that was used for the hole-injectionlayer and the hole-transport layer of the light-emitting element 1 andof PCPPn that was used for the hole-injection layer and thehole-transport layer of the light-emitting element 2 in this examplewere respectively as large as 3.48 eV and 3.53 eV, which hinders theoccurrence of energy transfer from the light-emitting layer.

The LUMO level of PCzPA is −2.77 eV and loss of carriers due to leakageof electrons from the light-emitting layer might occur. In contrast, theLUMO levels of PCPN and PCPPn are respectively as shallow as −2.29 eVand −2.25 eV, which hinders the occurrence of leakage of electrons fromthe respective light-emitting layers. Therefore, the light-emittingelement 1 and the light-emitting element 2 were able to obtain highefficiency. In addition, the HOMO level of PCzPA is −5.69 eV, which isclose to −5.70 eV that is the HOMO level of CzPA that is a host materialof the adjacent light-emitting layer; thus, an excellent hole-injectionproperty is obtained. The HOMO levels of PCPN and PCPPn are also as deepas −5.77 eV and −5.78 eV, respectively; thus, excellent hole-injectionproperties are obtained. In addition, the light-emitting elements 1 and2 both can be driven at a voltage as low as that of the comparativelight-emitting element 1, and thus have excellent carrier transfer.

Note that PCzPA is one of the materials that have excellenthole-transport properties and long lifetime.

Further, a reliability test was conducted on the manufacturedlight-emitting element 1, light-emitting element 2, and comparativelight-emitting element 1 were performed. In the reliability test, theinitial luminance was set at 5000 cd/m², these elements were driven at aconstant current density, and the luminance was measured at regularintervals. The results obtained by the reliability test are shown inFIG. 34. In FIG. 34, the horizontal axis represents the current flowtime (hour) and the vertical axis represents the percentage of luminanceto the initial luminance at each time, that is, normalized luminance(%).

According to FIG. 34, a reduction in the luminance of each of thelight-emitting element 1, the light-emitting element 2, and thecomparative light-emitting element 1 with time does not easily occur andthe lifetime of each of the elements is long. The light-emitting element1, the light-emitting element 2, and the comparative light-emittingelement 1 maintained 52% of the initial luminance even after beingdriven for 210 hours.

As described above, the carbazole compound of one embodiment of thepresent invention is used for a hole-injection layer and ahole-transport layer, whereby an element with high emission efficiencycan be obtained. The reasons for the above are probably as follows: theLUMO level of the carbazole compound of one embodiment of the presentinvention is shallow enough to suppress leakage of electrons from alight-emitting layer; the HOMO level is deep enough to make a propertyof injecting holes into a light-emitting layer excellent; and the bandgap is wide enough to suppress a reduction in efficiency due to energytransfer of excitons.

Further, it was indicated that when the carbazole compound of oneembodiment of the present invention is used for a hole-injection layerand a hole-transport layer, a light-emitting element with low drivevoltage can be manufactured.

Further, it was indicated that when the carbazole compound of oneembodiment of the present invention is used for a hole-injection layerand a hole-transport layer, a light-emitting element with long lifetimecan be manufactured.

Example 10

In this example, manufacturing methods of light-emitting elements eachof which is one embodiment of the present invention and measurementresults of the element characteristics will be described together withthe measurement results of a comparative light-emitting element.

Manufacturing methods of a light-emitting element 3, a light-emittingelement 4, and a comparative light-emitting element 2 will be describedbelow. Note that element structures of the light-emitting elementsmanufactured in this example are similar to that illustrated in FIG. 29.In addition, organic compounds used in this example were similar tothose in Example 9; therefore, the description of the organic compoundsis omitted.

(Light-Emitting Element 3)

The light-emitting element 3 was manufactured in a manner similar tothat of the light-emitting element 1 in Example 9 except for thehole-injection layer 1111 and the hole-transport layer 1112.

In the light-emitting element 3, a film of molybdenum(VI) oxide wasformed to a thickness of 10 nm by evaporation on the first electrode1101 to form the hole-injection layer 1111.

Next, PCPN synthesized in Example 1 was deposited to a thickness of 30nm on the hole-injection layer 1111 to form the hole-transport layer1112.

(Light-Emitting Element 4)

The light-emitting element 4 was manufactured in a manner similar tothat of the light-emitting element 3 except for the hole-transport layer1112.

In the light-emitting element 4, PCPPn synthesized in Example 2 wasdeposited to a thickness of 30 nm to form the hole-transport layer 1112.

(Comparative Light-Emitting Element 2)

The comparative light-emitting element 2 was manufactured in a mannersimilar to that of the light-emitting element 3 except for thehole-transport layer 1112.

In the comparative light-emitting element 2, PCzPA was deposited to athickness of 30 nm to form the hole-transport layer 1112.

Table 4 shows the element structures of the light-emitting element 3,the light-emitting element 4, and the comparative light-emitting element2 that were manufactured as described above.

TABLE 4 Light-Emitting Light-Emitting Comparative Light- Element 3Element 4 Emitting Element 2 First Electrode ITSO ITSO ITSO 1101 110 nm 110 nm  110 nm  Hole-injection Layer MoOx MoOx MoOx 1111 10 nm 10 nm 10nm Hole-transport layer PCPN PCPPn PCzPA 1112 30 nm 30 nm 30 nmLight-emitting layer CzPA: CzPA: CzPA: 1113 1,6FLPAPrn 1,6FLPAPrn1,6FLPAPrn (=1:0.05) (=1:0.05) (=1:0.05) 30 nm 30 nm 30 nmElectron-transport 1114a CzPA CzPA CzPA layer 10 nm 10 nm 10 nm 1114bBPhen BPhen BPhen 15 nm 15 nm 15 nm Electron-injection layer LiF LiF LiF1115  1 nm  1 nm  1 nm Second Electrode Al Al Al 1103 200 nm  200 nm 200 nm  *The mixture ratios are all represented in weight ratios.

In a glove box containing a nitrogen atmosphere, the light-emittingelement 3, the light-emitting element 4, and the comparativelight-emitting element 2 were sealed so as not to be exposed to the air.After that, the operating characteristics of these elements weremeasured. Note that the measurement was carried out at room temperature(in an atmosphere kept at 25° C.).

Note that the light-emitting element 3, the light-emitting element 4,and the comparative light-emitting element 2 were formed over the samesubstrate. In addition, in the above three light-emitting elements, therespective components other than the hole-transport layers were formedat the same time, and the operating characteristics of threelight-emitting elements were measured at the same time.

Table 5 shows the voltage (V), current density (mA/cm²), CIEchromaticity coordinates (x,y), luminance (cd/m²), current efficiency(cd/A), power efficiency (lm/W), and external quantum efficiency (%) ofeach of the light-emitting element 3, the light-emitting element 4, andthe comparative light-emitting element 2 at a luminance of about 1000cd/m².

TABLE 5 Light-Emitting Light-Emitting Comparative Light- Element 3Element 4 Emitting Element 2 Voltage (V) 3.2 3.2 3.4 Current density(mA/cm²) 6.9 6.2 8.9 Chromaticity coordinates (0.15, 0.25) (0.15, 0.26)(0.15, 0.24) (x, y) Luminance (cd/m²) 930 820 920 Current efficiency(cd/A) 13 13 10 Power efficiency (lm/W) 13 13 9.5 External quantum 8.18.0 6.5 efficiency (%)

FIG. 35 shows the emission spectra of the light-emitting element 3, thelight-emitting element 4, and the comparative light-emitting element 2.In FIG. 35, the horizontal axis represents the wavelength (nm) and thevertical axis represents the emission intensity (arbitrary unit). FIG.36, FIG. 37, and FIG. 38 respectively show the voltage-luminancecharacteristics, the luminance-current efficiency characteristics, andthe luminance-power efficiency characteristics of the light-emittingelement 3, the light-emitting element 4, and the comparativelight-emitting element 2. In FIG. 36, the vertical axis represents theluminance (cd/m²) and the horizontal axis represents the voltage (V). InFIG. 37, the vertical axis represents the current efficiency (cd/A) andthe horizontal axis represents the luminance (cd/m²). In FIG. 38, thevertical axis represents the power efficiency (lm/W) and the horizontalaxis represents the luminance (cd/m²).

According to FIG. 35, all of the emission spectra of the light-emittingelement 3, the light-emitting element 4, and the comparativelight-emitting element 2 have peaks around 470 nm. The CIE chromaticitycoordinates in Table 5 also show that the light-emitting element 3, thelight-emitting element 4, and the comparative light-emitting element 2exhibit blue light emission originating from 1,6FLPAPrn and that all theelements have excellent carrier balance.

Further, FIG. 36, FIG. 37, FIG. 38, and Table 5 show that thelight-emitting element 3 and the light-emitting element 4 have higherefficiency than the comparative light-emitting element 2. The reasonsfor the above are probably as follows: the band gaps of PCPN used forthe hole-transport layer of the light-emitting element 3 and of PCPPnused for the hole-transport layer of the light-emitting element 4 inthis example are wider than the band gap of PCzPA used for thecomparative light-emitting element 2; energy transfer from thelight-emitting layer does not easily occur; and the LUMO levels of PCPNand PCPPn are shallow enough to suppress leakage of electrons.

Further, a reliability test was conducted on the manufacturedlight-emitting element 3, light-emitting element 4, and comparativelight-emitting element 2. In the reliability test, the initial luminancewas set at 5000 cd/m², these elements were operated at a constantcurrent density, and the luminance was measured at regular intervals.The results obtained by the reliability test are shown in FIG. 39. InFIG. 39, the horizontal axis represents the current flow time (hour) andthe vertical axis represents the percentage of luminance to the initialluminance at each time, that is, normalized luminance (%).

According to FIG. 39, a reduction in the luminance of each of thelight-emitting element 3, the light-emitting element 4, and thecomparative light-emitting element 2 with time does not easily occur andthe lifetime of each of the elements is long. The light-emitting element3, the light-emitting element 4, and the comparative light-emittingelement 2 respectively maintained 60%, 56%, and 54% of the initialluminance even after being driven for 150 hours.

In this example, a single film of molybdenum oxide was used for thehole-injection layer. The drive voltage of all the elements in thisexample was slightly higher than that in Example 9, in which the mixedmaterial of the carbazole compound of one embodiment of the presentinvention and molybdenum oxide was used for the hole-injection layer.This indicates that when a mixed material of the carbazole compound ofone embodiment of the present invention and molybdenum oxide is used fora hole-injection layer, an element with an excellent hole-injectionproperty can be obtained.

As described above, the carbazole compound of one embodiment of thepresent invention is used for a hole-injection layer and ahole-transport layer, whereby an element with high emission efficiencycan be manufactured. The reasons for the above are probably as follows:the LUMO level of the carbazole compound of one embodiment of thepresent invention is shallow enough to suppress leakage of electronsfrom a light-emitting layer; the HOMO level is deep enough to make aproperty of injecting holes into a light-emitting layer excellent; andthe band gap is wide enough to suppress a reduction in efficiency due toenergy transfer of excitons.

Further, it was indicated that when the carbazole compound of oneembodiment of the present invention is used for a hole-injection layerand a hole-transport layer, a light-emitting element with long lifetimecan be obtained.

Further, it was indicated that even in a light-emitting element in whicha hole-injection layer is formed of a single layer of molybdenum oxide,excellent characteristics can be obtained. Note that a hole-injectionlayer is preferably formed using a composite material, in which case ashort circuit of a light-emitting element which is attributed to filmquality of an anode can be prevented.

Example 11

In this example, manufacturing methods of a light-emitting element whichis one embodiment of the present invention and the measurement resultsof the element characteristics will be described together with themeasurement results of a comparative light-emitting element.

Manufacturing methods of a light-emitting element 5 and a comparativelight-emitting element 3 will be described below. Note that elementstructures of the light-emitting elements manufactured in this exampleare similar to that illustrated in FIG. 29. In addition, organiccompounds used in this example were similar to those in Example 9;therefore, the description of the organic compounds is omitted.

(Light-Emitting Element 5)

The light-emitting element 5 was manufactured in a manner similar tothat of the light-emitting element 1 in Example 9 except for thehole-injection layer 1111 and the hole-transport layer 1112.

In the light-emitting element 5, the hole-injection layer 1111 wasformed in such a manner that9-(1-naphthyl)-3-[4-(1-naphthyl)-phenyl]-9H-carbazole (abbreviation:NCPN) synthesized in Example 6 and molybdenum(VI) oxide wereco-evaporated on the first electrode 1101. The thickness of thehole-injection layer 1111 was 50 nm. The weight ratio of NCPN tomolybdenum(VI) oxide was adjusted to 4:2 (=NCPN: molybdenum oxide).

Next, NCPN was deposited to a thickness of 10 nm on the hole-injectionlayer 1111 to form the hole-transport layer 1112.

(Comparative Light-Emitting Element 3)

The comparative light-emitting element 3 was manufactured in a mannersimilar to that of the comparative light-emitting element 1 in Example9.

Table 6 shows the element structures of the light-emitting element 5 andthe comparative light-emitting element 3 obtained as described above.

TABLE 6 Light-Emitting ComparativeLight- Element 5 Emitting Element 3First Electrode ITSO ITSO 1101 110 nm  110 nm  Hole-injection LayerNCPN:MoOx PCzPA:MoOx 1111 (=4:2) (=4:2) 50 nm 50 nm Hole-transport layerNCPN PCzPA 1112 10 nm 10 nm Light-emitting layer CzPA: CzPA: 11131,6FLPAPrn 1,6FLPAPrn (=1:0.05) (=1:0.05) 30 nm 30 nm Electron-transport1114a CzPA CzPA layer 10 nm 10 nm 1114b BPhen BPhen 15 nm 15 nmElectron-injection layer LiF LiF 1115  1 nm  1 nm Second Electrode Al Al1103 200 nm  200 nm  *The mixture ratios are all represented in weightratios.

In a glove box containing a nitrogen atmosphere, the light-emittingelement 5 and the comparative light-emitting element 3 were sealed so asnot to be exposed to the air. After that, the operating characteristicsof these elements were measured. Note that the measurement was carriedout at room temperature (in an atmosphere kept at 25° C.).

Note that the light-emitting element 5 and the comparativelight-emitting element 3 were formed over the same substrate. Inaddition, in the above two light-emitting elements, the respectivecomponents other than the hole-injection layers and the hole-transportlayers were formed at the same time, and the operating characteristicsof the two light-emitting elements were measured at the same time.

Table 7 shows the voltage (V), current density (mA/cm²), CIEchromaticity coordinates (x,y), luminance (cd/m²), current efficiency(cd/A), power efficiency (lm/W), and external quantum efficiency (%) ofeach of the light-emitting element 5 and the comparative light-emittingelement 3 at a luminance of about 1000 cd/m².

TABLE 7 Light-Emitting Comparative Light- Element 5 Emitting Element 3Voltage (V) 3.1 3.0 Current density (mA/cm²) 11 11 Chromaticitycoordinates (0.15, 0.22) (0.15, 0.22) (x, y) Luminance (cd/m²) 1000 800Current efficiency (cd/A) 9.2 7.5 Power efficiency (lm/W) 9.5 7.8External quantum 6.2 5.1 efficiency (%)

FIG. 40 shows the emission spectra of the light-emitting element 5 andthe comparative light-emitting element 3. In FIG. 40, the horizontalaxis represents the wavelength (nm) and the vertical axis represents theemission intensity (arbitrary unit). FIG. 41, FIG. 42, and FIG. 43respectively show the voltage-luminance characteristics, theluminance-current efficiency characteristics, and the luminance-powerefficiency characteristics of the light-emitting element 5 and thecomparative light-emitting element 3. In FIG. 41, the vertical axisrepresents the luminance (cd/m²) and the horizontal axis represents thevoltage (V). In FIG. 42, the vertical axis represents the currentefficiency (cd/A) and the horizontal axis represents the luminance(cd/m²). In FIG. 43, the vertical axis represents the power efficiency(lm/W) and the horizontal axis represents the luminance (cd/m²).

According to FIG. 40, all of the emission spectra of the light-emittingelement 5 and the comparative light-emitting element 3 have peaks around470 nm. The CIE chromaticity coordinates in Table 7 also show that thelight-emitting element 5 and the comparative light-emitting element 3exhibit blue light emission originating from 1,6FLPAPrn and that all theelements have excellent carrier balance.

Further, FIG. 41, FIG. 42, FIG. 43, and Table 7 show that thelight-emitting element 5 has higher efficiency than the comparativelight-emitting element 3. The reasons for the above are probably asfollows: the band gap of NCPN used for the hole-injection layer and thehole-transport layer of the light-emitting element 5 in this example iswider than the band gap of PCzPA used for the comparative light-emittingelement 3; energy transfer from the light-emitting layer does not easilyoccur; and the LUMO level of NCPN is shallow enough to prevent electronsfrom passing through the light-emitting layer.

Further, FIGS. 41 to 43 and Table 7 show that the light-emitting element5 and the comparative light-emitting element 3 can be driven at lowvoltage.

Further, a reliability test was conducted on the manufacturedlight-emitting element 5 and comparative light-emitting element 3. Inthe reliability test, the initial luminance was set at 5000 cd/m², theseelements were operated at a constant current density, and the luminancewas measured at regular intervals. The results obtained by thereliability test are shown in FIG. 44. In FIG. 44, the horizontal axisrepresents the current flow time (hour) and the vertical axis representsthe percentage of luminance to the initial luminance at each time, thatis, normalized luminance (%).

As shown in FIG. 44, a reduction in the luminance of each of thelight-emitting element 5 and the comparative light-emitting element 3with time does not easily occur and the lifetime of each of the elementsis long. The light-emitting element 5 and the comparative light-emittingelement 3 respectively maintained 62% and 57% of the initial luminanceeven after being driven for 130 hours.

As described above, the carbazole compound of one embodiment of thepresent invention is used for a hole-injection layer and ahole-transport layer, whereby an element with high emission efficiencycan be manufactured. The reasons for the above are probably as follows:the LUMO level of the carbazole compound of one embodiment of thepresent invention is shallow enough to suppress leakage of electronsfrom a light-emitting layer; the HOMO level is deep enough to make aproperty of injecting holes into a light-emitting layer excellent; andthe band gap is wide enough to suppress a reduction in efficiency due toenergy transfer of excitons.

Further, it was indicated that when the carbazole compound of oneembodiment of the present invention is used for a hole-injection layerand a hole-transport layer, a light-emitting element with low drivevoltage can be manufactured.

Further, it was indicated that when the carbazole compound of oneembodiment of the present invention is used for a hole-injection layerand a hole-transport layer, a light-emitting element with long lifetimecan be manufactured.

Example 12

In this example, manufacturing methods of a light-emitting element whichis one embodiment of the present invention and the measurement resultsof the element characteristics will be described together with themeasurement results of a comparative light-emitting element.

Manufacturing methods of a light-emitting element 6 and a comparativelight-emitting element 4 will be described below. Note that elementstructures of the light-emitting elements manufactured in this exampleare similar to that illustrated in FIG. 29. In addition, organiccompounds used in this example were similar to those in Example 9 wereused in this example; therefore, the description of the organiccompounds is omitted.

(Light-Emitting Element 6)

The light-emitting element 6 was manufactured in a manner similar tothat of the light-emitting element 1 in Example 9 except for thehole-injection layer 1111 and the hole-transport layer 1112.

In the light-emitting element 6, the hole-injection layer 1111 wasformed in such a manner that3,6-bis-[4-(1-naphthyl)-phenyl]-9-phenyl-9H-carbazole (abbreviation:NP2PC) synthesized in Example 7 and molybdenum(VI) oxide wereco-evaporated on the first electrode 1101. The thickness of thehole-injection layer 1111 was 50 nm. The weight ratio of NP2PC tomolybdenum(VI) oxide was adjusted to 4:2 (=NP2PC: molybdenum oxide).

Next, NP2PC was deposited to a thickness of 10 nm on the hole-injectionlayer 1111 to form the hole-transport layer 1112.

(Comparative Light-Emitting Element 4)

The comparative light-emitting element 4 was manufactured in a mannersimilar to that of the comparative light-emitting element 1 in Example9.

Table 8 shows the element structures of the light-emitting element 6 andthe comparative light-emitting element 4 obtained as described above.

TABLE 8 Light-Emitting Comparative Light- Element 6 Emitting Element 4First Electrode ITSO ITSO 1101 110 nm  110 nm  Hole-injection LayerNP2PC:MoOx PCzPA:MoOx 1111 (=4:2) (=4:2) 50 nm 50 nm Hole-transportlayer NP2PC PCzPA 1112 10 nm 10 nm Light-emitting layer CzPA: CzPA: 11131,6FLPAPrn 1,6FLPAPrn (=1:0.05) (=1:0.05) 30 nm 30 nm Electron-transport1114a CzPA CzPA layer 10 nm 10 nm 1114b BPhen BPhen 15 nm 15 nmElectron-injection layer LiF LiF 1115  1 nm  1 nm Second Electrode Al Al1103 200 nm  200 nm  *The mixture ratios are all represented in weightratios.

In a glove box containing a nitrogen atmosphere, the light-emittingelement 6 and the comparative light-emitting element 4 were sealed so asnot to be exposed to the air. After that, the operating characteristicsof these elements were measured. Note that the measurement was carriedout at room temperature (in an atmosphere kept at 25° C.).

Note that the light-emitting element 6 and the comparativelight-emitting element 4 were formed over the same substrate. Inaddition, in the above two light-emitting elements, the respectivecomponents other than the hole-injection layers and the hole-transportlayers were formed at the same time, and the operating characteristicsof the two light-emitting elements were measured at the same time.

Table 9 shows the voltage (V), current density (mA/cm²), CIEchromaticity coordinates (x,y), luminance (cd/m²), current efficiency(cd/A), power efficiency (lm/W), and external quantum efficiency (%) ofeach of the light-emitting element 6 and the comparative light-emittingelement 4 at a luminance of about 1000 cd/m².

TABLE 9 Light-Emitting Comparative Light- Element 6 Emitting Element 4Voltage (V) 3.1 3.1 Current density (mA/cm²) 13 15 Chromaticitycoordinates (0.15, 0.23) (0.15, 0.22) (x, y) Luminance (cd/m²) 1120 1090Current efficiency (cd/A) 8.9 7.4 Power efficiency (lm/W) 9.1 7.6External quantum 5.8 5.1 efficiency (%)

FIG. 45 shows the emission spectra of the light-emitting element 6 andthe comparative light-emitting element 4. In FIG. 45, the horizontalaxis represents the wavelength (nm) and the vertical axis represents theemission intensity (arbitrary unit). FIG. 46, FIG. 47, and FIG. 48respectively show the voltage-luminance characteristics, theluminance-current efficiency characteristics, and the luminance-powerefficiency characteristics of the light-emitting element 6 and thecomparative light-emitting element 4. In FIG. 46, the vertical axisrepresents the luminance (cd/m²) and the horizontal axis represents thevoltage (V). In FIG. 47, the vertical axis represents the currentefficiency (cd/A) and the horizontal axis represents the luminance(cd/m²). In FIG. 48, the vertical axis represents the power efficiency(lm/W) and the horizontal axis represents the luminance (cd/m²).

According to FIG. 45, all of the emission spectra of the light-emittingelement 6 and the comparative light-emitting element 4 have peaks around470 nm. The CIE chromaticity coordinates in Table 9 also show that thelight-emitting element 6 and the comparative light-emitting element 4exhibit blue light emission originating from 1,6FLPAPrn and that all theelements have excellent carrier balance.

Further, FIG. 46, FIG. 47, FIG. 48, and Table 9 show that thelight-emitting element 6 has higher efficiency than the comparativelight-emitting element 4. The reasons for the above are probably asfollows: the band gap of NP2PC used for the hole-injection layer and thehole-transport layer of the light-emitting element 6 in this example iswider than the band gap of PCzPA used for the comparative light-emittingelement 4; energy transfer from the light-emitting layer does not easilyoccur; and the LUMO level of NP2PC is shallow enough to preventelectrons from passing through the light-emitting layer.

Further, FIGS. 46 to 48 and Table 9 show that the light-emitting element6 and the comparative light-emitting element 4 can be driven at lowvoltage.

Further, a reliability test was conducted on the manufacturedlight-emitting element 6 and comparative light-emitting element 4. Inthe reliability test, the initial luminance was set at 5000 cd/m², theseelements were operated at a constant current density, and the luminancewas measured at regular intervals. The results obtained by thereliability test are shown in FIG. 49. In FIG. 49, the horizontal axisrepresents the current flow time (hour) and the vertical axis representsthe percentage of luminance to the initial luminance at each time, thatis, normalized luminance (%).

As shown in FIG. 49, a reduction in the luminance of each of thelight-emitting element 6 and the comparative light-emitting element 4with time does not easily occur and the lifetime of each of the elementsis long. The light-emitting element 6 and the comparative light-emittingelement 4 respectively maintained 63% and 57% of the initial luminanceeven after being driven for 130 hours.

As described above, the carbazole compound of one embodiment of thepresent invention is used for a hole-injection layer and ahole-transport layer, whereby an element with high emission efficiencycan be manufactured. The reasons for the above are probably as follows:the LUMO level of the carbazole compound of one embodiment of thepresent invention is shallow enough to suppress leakage of electronsfrom a light-emitting layer; the HOMO level is deep enough to make aproperty of injecting holes into a light-emitting layer excellent; andthe band gap is wide enough to suppress a reduction in efficiency due toenergy transfer of excitons.

Further, it was indicated that when the carbazole compound of oneembodiment of the present invention is used for a hole-injection layerand a hole-transport layer, a light-emitting element with low drivevoltage can be manufactured.

Further, it was indicated that when the carbazole compound of oneembodiment of the present invention is used for a hole-injection layerand a hole-transport layer, a light-emitting element with long lifetimecan be manufactured.

Example 13

In this example, a manufacturing method of a light-emitting elementwhich is one embodiment of the present invention and measurement resultsof element characteristics will be described together with measurementresults of a comparative light-emitting element.

Manufacturing methods of a light-emitting element 7 and a comparativelight-emitting element 5 will be described below. Note that elementstructures of the light-emitting elements manufactured in this exampleare similar to that illustrated in FIG. 29. In addition, organiccompound used in this example were similar to those in Example 9;therefore, the description of the organic compounds is omitted.

(Light-Emitting Element 7)

The light-emitting element 7 was manufactured in a manner similar tothat of the light-emitting element 1 in Example 9 except for thehole-injection layer 1111 and the hole-transport layer 1112.

In the light-emitting element 7, the hole-injection layer 1111 wasformed in such a manner that3-[3-(9-phenanthryl)-phenyl]-9-phenyl-9H-carbazole (abbreviation:mPCPPn) synthesized in Example 4 and molybdenum(VI) oxide wereco-evaporated on the first electrode 1101. The thickness of thehole-injection layer 1111 was 50 nm. The weight ratio of mPCPPn tomolybdenum(VI) oxide was adjusted to 4:2 (=mPCPPn: molybdenum oxide).

Next, mPCPPn was deposited to a thickness of 10 nm on the hole-injectionlayer 1111 to form the hole-transport layer 1112.

(Comparative Light-Emitting Element 5)

The comparative light-emitting element 5 was manufactured in a mannersimilar to that of the comparative light-emitting element 1 in Example9.

Table 10 shows the element structures of the light-emitting element 7and the comparative light-emitting element 5 that were obtained asdescribed above.

TABLE 10 Light-Emitting Comparative Light- Element 7 Emitting Element 5First Electrode ITSO ITSO 1101 110 nm  110 nm  Hole-injection LayermPCPPn:MoOx PCzPA:MoOx 1111 (=4:2) (=4:2) 50 nm 50 nm Hole-transportlayer mPCPPn PCzPA 1112 10 nm 10 nm Light-emitting layer CzPA: CzPA:1113 1,6FLPAPrn 1,6FLPAPrn (=1:0.05) (=1:0.05) 30 nm 30 nmElectron-transport 1114a CzPA CzPA layer 10 nm 10 nm 1114b BPhen BPhen15 nm 15 nm Electron-injection layer LiF LiF 1115  1 nm  1 nm SecondElectrode Al Al 1103 200 nm  200 nm  *The mixture ratios are allrepresented in weight ratios.

In a glove box containing a nitrogen atmosphere, the light-emittingelement 7 and the comparative light-emitting element 5 were sealed so asnot to be exposed to the air. After that, the operating characteristicsof these elements were measured. Note that the measurement was carriedout at room temperature (in an atmosphere kept at 25° C.).

Note that the light-emitting element 7 and the comparativelight-emitting element 5 were formed over the same substrate. Inaddition, in the above two light-emitting elements, the respectivecomponents other than the hole-injection layers and the hole-transportlayers were formed at the same time, and the operating characteristicsof the two light-emitting elements were measured at the same time.

Table 11 shows the voltage (V), current density (mA/cm²), CIEchromaticity coordinates (x, y), luminance (cd/m²), current efficiency(cd/A), power efficiency (lm/W), and external quantum efficiency (%) ofeach of the light-emitting element 7 and the comparative light-emittingelement 5 at a luminance of about 1000 cd/m².

TABLE 11 Light-Emitting Comparative Light- Element 7 Emitting Element 5Voltage (V) 3.1 3.0 Current density (mA/cm²) 8.8 7.0 Chromaticitycoordinates (0.15, 0.20) (0.15, 0.20) (x, y) Luminance (cd/m²) 880 500Current efficiency (cd/A) 10 7.2 Power efficiency (lm/W) 10 7.5 Externalquantum 7.1 5.2 efficiency (%)

FIG. 50 shows the emission spectra of the light-emitting element 7 andthe comparative light-emitting element 5. In FIG. 50, the horizontalaxis represents the wavelength (nm) and the vertical axis represents theemission intensity (arbitrary unit). FIG. 51, FIG. 52, and FIG. 53respectively show the voltage-luminance characteristics, theluminance-current efficiency characteristics, and the luminance-powerefficiency characteristics of the light-emitting element 7 and thecomparative light-emitting element 5. In FIG. 51, the vertical axisrepresents the luminance (cd/m²) and the horizontal axis represents thevoltage (V). In FIG. 52, the vertical axis represents the currentefficiency (cd/A) and the horizontal axis represents the luminance(cd/m²). In FIG. 53, the vertical axis represents the power efficiency(lm/W) and the horizontal axis represents the luminance (cd/m²).

According to FIG. 50, all of the emission spectra of the light-emittingelement 7 and the comparative light-emitting element 5 have peaks around470 nm. The CIE chromaticity coordinates in Table 11 also show that thelight-emitting element 7 and the comparative light-emitting element 5exhibit blue light emission originating from 1,6FLPAPrn and that all theelements have excellent carrier balance.

Further, FIG. 51, FIG. 52, and Table 11 show that the light-emittingelement 7 has higher efficiency than the comparative light-emittingelement 5. The reasons for the above are probably as follows: the bandgap of mPCPPn used for the hole-injection layer and the hole-transportlayer of the light-emitting element 7 in this example is wider than theband gap of PCzPA used for the comparative light-emitting element 5;energy transfer from the light-emitting layer does not easily occur; andthe LUMO level of mPCPPn is shallow enough to prevent electrons frompassing through the light-emitting layer.

Further, FIG. 51, FIG. 52, FIG. 53, and Table 11 show that thelight-emitting element 7 and the comparative light-emitting element 5can be driven at low voltage.

As described above, the carbazole compound of one embodiment of thepresent invention is used for a hole-injection layer and ahole-transport layer, whereby an element with high emission efficiencycan be manufactured. The reasons for the above are probably as follows:the LUMO level of the carbazole compound of one embodiment of thepresent invention is shallow enough to suppress leakage of electronsfrom a light-emitting layer; the HOMO level is deep enough to make aproperty of injecting holes into a light-emitting layer excellent; andthe band gap is wide enough to suppress a reduction in efficiency due toenergy transfer of excitons.

Further, it was indicated that when the carbazole compound of oneembodiment of the present invention is used for a hole-injection layerand a hole-transport layer, a light-emitting element with low drivevoltage can be manufactured.

Example 14

In this example, a manufacturing method of a light-emitting elementwhich is one embodiment of the present invention and measurement resultsof element characteristics will be described together with measurementresults of a comparative light-emitting element.

Manufacturing methods of a light-emitting element 8 and a comparativelight-emitting element 6 will be described below. Note that elementstructures of the light-emitting elements manufactured in this exampleare similar to that illustrated in FIG. 29. The structural formula of anorganic compound used in this example is shown below. Note that theorganic compounds whose structural formulae have been already shown areomitted.

(Light-Emitting Element 8)

The light-emitting element 8 was manufactured in a manner similar tothat of the light-emitting element 7 in Example 13 except for the firstelectron-transport layer 1114 a.

In the light-emitting element 8, tris(8-quinolinolato)aluminum(III)(abbreviation: Alq) was deposited to a thickness of 10 nm on thelight-emitting layer 1113 to form the first electron-transport layer1114 a.

(Comparative Light-Emitting Element 6)

The comparative light-emitting element 6 was manufactured in a mannersimilar to that of the comparative light-emitting element 1 in Example 9except for the first electron-transport layer 1114 a.

In the light-emitting element 6, Alq was deposited to a thickness of 10nm on the light-emitting layer 1113 to form the first electron-transportlayer 1114 a.

Table 12 shows the element structures of the light-emitting element 8and the comparative light-emitting element 6 that were obtained asdescribed above.

TABLE 12 Light-Emitting Comparative Light- Element 8 Emitting Element 6First Electrode ITSO ITSO 1101 110 nm  110 nm  Hole-injection LayermPCPPn:MoOx PCzPA:MoOx (=4:2) (=4:2) 1111 50 nm 50 nm Hole-transportlayer mPCPPn PCzPA 1112 10 nm 10 nm Light-emitting layer CzPA:1,6FLPAPrnCzPA:1,6FLPAPrn 1113 (=1:0.05) (=1:0.05) 30 nm 30 nm Electron-transport1114a Alq Alq layer 10 nm 10 nm 1114b BPhen BPhen 15 nm 15 nmElectron-injection layer LiF LiF 1115  1 nm  1 nm Second Electrode Al Al1103 200 nm  200 nm  *The mixture ratios are all represented in weightratios.

In a glove box containing a nitrogen atmosphere, the light-emittingelement 8 and the comparative light-emitting element 6 were sealed so asnot to be exposed to the air. After that, the operating characteristicsof these elements were measured. Note that the measurement was carriedout at room temperature (in an atmosphere kept at 25° C.).

Note that the light-emitting element 8 and the comparativelight-emitting element 6 were formed over the same substrate. Inaddition, in the above two light-emitting elements, the respectivecomponents other than the hole-injection layers and the hole-transportlayers were formed at the same time, and the operating characteristicsof the two light-emitting elements were measured at the same time.

Table 13 shows the voltage (V), current density (mA/cm²), CIEchromaticity coordinates (x,y), luminance (cd/m²), current efficiency(cd/A), power efficiency (lm/W), and external quantum efficiency (%) ofeach of the light-emitting element 8 and the comparative light-emittingelement 6 at a luminance of about 1000 cd/m².

TABLE 13 Light-Emitting Comparative Light- Element 8 Emitting Element 6Voltage (V) 4.0 4.0 Current density (mA/cm²) 9.6 12 Chromaticitycoordinates (0.15, 0.21) (0.15, 0.20) (x, y) Luminance (cd/m²) 930 840Current efficiency (cd/A) 9.7 7.1 Power efficiency (lm/W) 7.7 5.5External quantum 6.9 5.1 efficiency (%)

FIG. 54 shows the emission spectra of the light-emitting element 8 andthe comparative light-emitting element 6. In FIG. 54, the horizontalaxis represents the wavelength (nm) and the vertical axis represents theemission intensity (arbitrary unit). FIG. 55, FIG. 56, and FIG. 57respectively show the voltage-luminance characteristics, theluminance-current efficiency characteristics, and the luminance-powerefficiency characteristics of the light-emitting element 8 and thecomparative light-emitting element 6. In FIG. 55, the vertical axisrepresents the luminance (cd/m²) and the horizontal axis represents thevoltage (V). In FIG. 56, the vertical axis represents the currentefficiency (cd/A) and the horizontal axis represents the luminance(cd/m²). In FIG. 57, the vertical axis represents the power efficiency(lm/W) and the horizontal axis represents the luminance (cd/m²).

According to FIG. 54, the emission spectra of the light-emitting element8 and the comparative light-emitting element 6 have peaks around 470 nm.The CIE chromaticity coordinates in Table 13 also show that thelight-emitting element 8 and the comparative light-emitting element 6exhibit blue light emission originating from 1,6FLPAPrn and that all theelements have excellent carrier balance.

Further, FIG. 55, FIG. 56, FIG. 57, and Table 13 show that thelight-emitting element 8 has higher efficiency than the comparativelight-emitting element 6. The reasons for the above are probably asfollows: the band gap of mPCPPn used for the hole-injection layer andthe hole-transport layer of the light-emitting element 8 in this exampleis wider than the band gap of PCzPA used for the comparativelight-emitting element 6; energy transfer from the light-emitting layerdoes not easily occur; and the LUMO level of mPCPPn is shallow enough toprevent electrons from passing through the light-emitting layer.

Further, FIG. 55, FIG. 56, and Table 13 show that the light-emittingelement 8 and the comparative light-emitting element 6 can be driven atlow voltage.

Further, a reliability test was conducted on the manufacturedlight-emitting element 8 and comparative light-emitting element 6. Inthe reliability test, the initial luminance was set at 5000 cd/m², theseelements were operated at a constant current density, and the luminancewas measured at regular intervals. The results obtained by thereliability test are shown in FIG. 58. In FIG. 58, the horizontal axisrepresents the current flow time (hour) and the vertical axis representsthe percentage of luminance to the initial luminance at each time, thatis, normalized luminance (%).

As shown in FIG. 58, a reduction in the luminance of each of thelight-emitting element 8 and the comparative light-emitting element 6with time does not easily occur and the lifetime of each of the elementsis long. The light-emitting element 8 and the comparative light-emittingelement 6 respectively maintained 83% and 81% of the initial luminanceeven after being driven for 70 hours.

As described above, the carbazole compound of one embodiment of thepresent invention is used for a hole-injection layer and ahole-transport layer, whereby an element with high emission efficiencycan be manufactured. The reasons for the above are probably as follows:the LUMO level of the carbazole compound of one embodiment of thepresent invention is shallow enough to suppress leakage of electronsfrom a light-emitting layer; the HOMO level is deep enough to make aproperty of injecting holes into a light-emitting layer excellent; andthe band gap is wide enough to suppress a reduction in efficiency due toenergy transfer of excitons.

Further, it was indicated that when the carbazole compound of oneembodiment of the present invention is used for a hole-injection layerand a hole-transport layer, a light-emitting element with low drivevoltage can be manufactured.

Further, it was indicated that when the carbazole compound of oneembodiment of the present invention is used for a hole-injection layerand a hole-transport layer, a light-emitting element with long lifetimecan be manufactured.

Example 15

In this example, a manufacturing method of a light-emitting elementwhich is one embodiment of the present invention and measurement resultsof element characteristics will be described together with measurementresults of a comparative light-emitting element.

Manufacturing methods of a light-emitting element 9 and a comparativelight-emitting element 7 will be described below. Note that elementstructures of the light-emitting elements manufactured in this exampleare similar to that illustrated in FIG. 29. The structural formula of anorganic compound used in this example is shown below. Note that theorganic compounds whose structural formulae have been already shown areomitted.

(Light-Emitting Element 9)

The light-emitting element 9 was manufactured in a manner similar tothat of the light-emitting element 1 in Example 9 except for thehole-injection layer 1111, the hole-transport layer 1112, thelight-emitting layer 1113, and the first electron-transport layer 1114a.

In the light-emitting element 9, the hole-injection layer 1111 wasformed in such a manner that9-phenyl-3-[3-(triphenylen-2-yl)-phenyl]-9H-carbazole (abbreviation:mPCzPTp) synthesized in Example 5 and molybdenum(VI) oxide wereco-evaporated on the first electrode 1101. The thickness of thehole-injection layer 1111 was 50 nm. The weight ratio of mPCzPTp tomolybdenum(VI) oxide was adjusted to 4:2 (=mPCzPTp: molybdenum oxide).

Next, mPCzPTp was deposited to a thickness of 10 nm on thehole-injection layer 1111 to form the hole-transport layer 1112.

Furthermore, 4-[3-(triphenylen-2-yl)phenyl]dibenzothiophene(abbreviation: mDBTPTp-II) andtris(2-phenylpyridinato-N,C^(2′))iridium(III) (abbreviation: Ir(ppy)₃)were co-evaporated to form the light-emitting layer 1113 on thehole-transport layer 1112. Here, the weight ratio of mDBTPTp-II toIr(ppy)₃ was adjusted to be 1:0.06 (=mDBTPTp-II: Ir(ppy)₃. The thicknessof the light-emitting layer 1113 was 40 nm.

Next, Alq was deposited to a thickness of 15 nm on the light-emittinglayer 1113 to form the first electron-transport layer 1114 a.

(Comparative Light-Emitting Element 7)

The comparative light-emitting element 7 was manufactured in a mannersimilar to that of the comparative light-emitting element 1 in Example 9except for the light-emitting layer 1113 and the firstelectron-transport layer 1114 a.

In the comparative light-emitting element 7, structures of thelight-emitting layer 1113 and the first electron-transport layer 1114 aare similar to those in the above light-emitting element 9.

Table 14 shows the element structures of the light-emitting element 9and the comparative light-emitting element 7 that were obtained asdescribed above.

TABLE 14 Light-Emitting Comparative Light- Element 9 Emitting Element 7First Electrode ITSO ITSO 1101 110 nm  110 nm  Hole-injection LayermPCzPTp:MoOx PCzPA:MoOx 1111 (=4:2) (=4:2) 50 nm 50 nm Hole-transportlayer mPCzPTp PCzPA 1112 10 nm 10 nm Light-emitting layer mDBTPTp II:mDBTPTp II: 1113 Ir(ppy)3 Ir(ppy)3 (=1:0.06) (=1:0.06) 40 nm 40 nmElectron-transport 1114a Alq Alq layer 15 nm 15 nm 1114b BPhen BPhen 15nm 15 nm Electron-injection layer LiF LiF 1115  1 nm  1 nm SecondElectrode Al Al 1103 200 nm  200 nm  *The mixture ratios are allrepresented in weight ratios.

In a glove box containing a nitrogen atmosphere, the light-emittingelement 9 and the comparative light-emitting element 7 were sealed so asnot to be exposed to the air. After that, the operating characteristicsof these elements were measured. Note that the measurement was carriedout at room temperature (in an atmosphere kept at 25° C.).

Note that the light-emitting element 9 and the comparativelight-emitting element 7 were formed over the same substrate. Inaddition, in the above two light-emitting elements, the respectivecomponents other than the hole-injection layers and the hole-transportlayers were formed at the same time, and the operating characteristicsof the two light-emitting elements were measured at the same time.

Table 15 shows the voltage (V), current density (mA/cm²), CIEchromaticity coordinates (x,y), luminance (cd/m²), current efficiency(cd/A), power efficiency (lm/W), and external quantum efficiency (%) ofeach of the light-emitting element 9 and the comparative light-emittingelement 7 at a luminance of about 1000 cd/m².

TABLE 15 Light-Emitting Comparative Light- Element 9 Emitting Element 7Voltage (V) 7.0 7.0 Current density (mA/cm²) 2.1 3.5 Chromaticitycoordinates (0.34, 0.61) (0.34, 0.61) (x, y) Luminance (cd/m²) 990 910Current efficiency (cd/A) 47 26 Power efficiency (lm/W) 21 12 Externalquantum 14 8.0 efficiency (%)

FIG. 59 shows the emission spectra of the light-emitting element 9 andthe comparative light-emitting element 7. In FIG. 59, the horizontalaxis represents the wavelength (nm) and the vertical axis represents theemission intensity (arbitrary unit). FIG. 60 and FIG. 61 respectivelyshow the voltage-luminance characteristics and the luminance-powerefficiency characteristics of the light-emitting element 9 and thecomparative light-emitting element 7. In FIG. 60, the vertical axisrepresents the luminance (cd/m²) and the horizontal axis represents thevoltage (V). In FIG. 61, the vertical axis represents the currentefficiency (cd/A) and the horizontal axis represents the luminance(cd/m²).

According to FIG. 59, the emission spectra of the light-emitting element9 and the comparative light-emitting element 7 have peaks around 520 nm.The CIE chromaticity coordinates in Table 15 also show that thelight-emitting element 9 and the comparative light-emitting element 7exhibit green phosphorescence emission originating from Ir(ppy)₃ andthat all the elements have excellent carrier balance.

Further, FIG. 60, FIG. 61, and Table 15 show that the light-emittingelement 9 has higher efficiency than the comparative light-emittingelement 7. The reasons for the above are probably as follows: the bandgap of mPCzPTp used for the hole-injection layer and the hole-transportlayer of the light-emitting element 9 in this example is wider than theband gap of PCzPA used for the comparative light-emitting element 7;energy transfer from the light-emitting layer does not easily occur; andthe LUMO level of mPCzPTp is shallow enough to prevent electrons frompassing through the light-emitting layer.

Further, FIG. 60, FIG. 61, and Table 15 show that the light-emittingelement 9 and the comparative light-emitting element 7 can be driven atlow voltage.

As described above, the carbazole compound of one embodiment of thepresent invention is used for a hole-injection layer and ahole-transport layer, whereby an element with high emission efficiencycan be manufactured. The reasons for the above are probably as follows:the LUMO level of the carbazole compound of one embodiment of thepresent invention is shallow enough to suppress leakage of electronsfrom a light-emitting layer; the HOMO level is deep enough to make aproperty of injecting holes into a light-emitting layer excellent; andthe band gap is wide enough to suppress a reduction in efficiency due toenergy transfer of excitons.

Further, it was indicated that when the carbazole compound of oneembodiment of the present invention is used for a hole-injection layerand a hole-transport layer, a light-emitting element with low drivevoltage can be manufactured.

Example 16

In this example, a manufacturing method of a light-emitting elementwhich is one embodiment of the present invention and measurement resultsof element characteristics will be described together with measurementresults of a comparative light-emitting element.

Manufacturing methods of a light-emitting element 10 and a comparativelight-emitting element 8 will be described below. The element structureof the light-emitting elements manufactured in this example isillustrated in FIG. 62. Note that organic compounds used in this exampleare similar to those in the above examples; therefore, the descriptionof the organic compounds is omitted.

(Light-Emitting Element 10)

The light-emitting element 10 was manufactured in a manner similar tothat of the light-emitting element 9 in Example 15 except for thelight-emitting layer 1113.

In the light-emitting element 10, a first light-emitting layer 1113 aand a second light-emitting layer 1113 b were stacked in this order onthe first electrode 1101 to form the light-emitting layer 1113.

The first light-emitting layer 1113 a was formed by co-evaporation ofmPCzPTp synthesized in Example 5 andtris(2-phenylpyridinato-N,C^(2′))iridium(III) (abbreviation: Ir(ppy)₃).Here, the weight ratio of mPCzPTp to Ir(ppy)₃ was adjusted to be 1:0.06(=mPCzPTp:Ir(ppy)₃). The thickness of the first light-emitting layer1113 a was 20 nm.

Next, 4-[3-(triphenylen-2-yl)phenyl]dibenzothiophene (abbreviation:mDBTPTp-II) and Ir(ppy)₃ were co-evaporated to form the secondlight-emitting layer 1113 b on the first light-emitting layer 1113 a.The weight ratio of mDBTPTp-II to Ir(ppy)₃ was adjusted to be 1:0.06(=mDBTPTp-II: Ir(ppy)₃). The thickness of the second light-emittinglayer 1113 b was 20 nm.

(Comparative Light-Emitting Element 8)

The comparative light-emitting element 8 was manufactured in a mannersimilar to that of the comparative light-emitting element 7 in Example15 except for the light-emitting layer 1113.

In the comparative light-emitting element 8, a structure of thelight-emitting layer 1113 was similar to that in the abovelight-emitting element 10.

Table 16 shows the element structures of the light-emitting element 10and the comparative light-emitting element 8 that were obtained asdescribed above.

TABLE 16 Light-Emitting Comparative Light- Element 10 Emitting Element 8First Electrode ITSO ITSO 1101 110 nm  110 nm  Hole-injection LayermPCzPTp:MoOx PCzPA:MoOx 1111 (=4:2) (=4:2) 50 nm 50 nm Hole-transportlayer mPCzPTp PCzPA 1112 10 nm 10 nm Light-Emitting Layer 1113a mPCzPTp:mPCzPTp: 1113 Ir(ppy)3 Ir(ppy)3 (=1:0.06) (=1:0.06) 20 nm 20 nm 1113bmDBTPTp- II: mDBTPTp- II: Ir(ppy)3 Ir(ppy)3 (=1:0.06) (=1:0.06) 20 nm 20nm Electron-transport 1114a Alq Alq layer 15 nm 15 nm 1114b BPhen BPhen15 nm 15 nm Electron-injection layer LiF LiF 1115  1 nm  1 nm SecondElectrode Al Al 1103 200 nm  200 nm  *The mixture ratios are allrepresented in weight ratios.

In a glove box containing a nitrogen atmosphere, the light-emittingelement 10 and the comparative light-emitting element 8 were sealed soas not to be exposed to the air. After that, the operatingcharacteristics of these elements were measured. Note that themeasurement was carried out at room temperature (in an atmosphere keptat 25° C.).

Note that the light-emitting element 10 and the comparativelight-emitting element 8 were formed over the same substrate. Inaddition, in the above two light-emitting elements, the respectivecomponents other than the hole-injection layers and the hole-transportlayers were formed at the same time, and the operating characteristicsof the two light-emitting elements were measured at the same time.

Table 17 shows the voltage (V), current density (mA/cm²), CIEchromaticity coordinates (x,y), luminance (cd/m²), current efficiency(cd/A), power efficiency (lm/W), and external quantum efficiency (%) ofeach of the light-emitting element 10 and the comparative light-emittingelement 8 at a luminance of about 1000 cd/m².

TABLE 17 Light-Emitting Comparative Light- Element 10 Emitting Element 8Voltage (V) 6.8 6.8 Current density (mA/cm²) 2.4 3.9 Chromaticitycoordinates (0.34, 0.61) (0.33, 0.61) (x, y) Luminance (cd/m²) 1100 1100Current efficiency (cd/A) 47 28 Power efficiency (lm/W) 22 13 Externalquantum 14 8.3 efficiency (%)

FIG. 63 shows the emission spectra of the light-emitting element 10 andthe comparative light-emitting element 8. In FIG. 63, the horizontalaxis represents the wavelength (nm) and the vertical axis represents theemission intensity (arbitrary unit). FIG. 64 and FIG. 65 respectivelyshow the voltage-luminance characteristics and the luminance-powerefficiency characteristics of the light-emitting element 10 and thecomparative light-emitting element 8. In FIG. 64, the vertical axisrepresents the luminance (cd/m²) and the horizontal axis represents thevoltage (V). In FIG. 65, the vertical axis represents the currentefficiency (cd/A) and the horizontal axis represents the luminance(cd/m²).

According to FIG. 63, the emission spectra of the light-emitting element10 and the comparative light-emitting element 8 have peaks around 515nm. The CIE chromaticity coordinates in Table 17 also show that thelight-emitting element 10 and the comparative light-emitting element 8exhibit green phosphorescence emission originating from Ir(ppy)₃ andthat the elements both have excellent carrier balance. Further, in thelight-emitting element 10 and the comparative light-emitting element 8,the carbazole compound according to one embodiment of the presentinvention is used as a host material of a phosphorescent compound whichemits green light, and the T1 level of the carbazole compound accordingto one embodiment of the present invention was confirmed to besufficiently high (higher than the T1 level of at least a phosphorescentcompound which emits green light).

Further, FIG. 64, FIG. 65, and Table 17 show that the light-emittingelement 10 has higher efficiency than the comparative light-emittingelement 8. The reasons for the above are probably as follows: the bandgap of mPCzPTp used for the hole-injection layer and the hole-transportlayer of the light-emitting element 10 in this example is wider than theband gap of PCzPA used for the comparative light-emitting element 8;energy transfer from the light-emitting layer does not easily occur; andthe LUMO level of mPCzPTp is shallow enough to prevent electrons frompassing through the light-emitting layer.

Further, FIG. 64, FIG. 65, and Table 17 show that the light-emittingelement 10 and the comparative light-emitting element 8 can be driven atlow voltage.

As described above, the carbazole compound of one embodiment of thepresent invention is used for a hole-injection layer and ahole-transport layer, whereby an element with high emission efficiencycan be manufactured. The reasons for the above are probably as follows:the LUMO level of the carbazole compound of one embodiment of thepresent invention is shallow enough to suppress leakage of electronsfrom a light-emitting layer; the HOMO level is deep enough to make aproperty of injecting holes into a light-emitting layer excellent; andthe band gap is wide enough to suppress a reduction in efficiency due toenergy transfer of excitons.

Further, it was indicated that when the carbazole compound of oneembodiment of the present invention is used for a hole-injection layerand a hole-transport layer, a light-emitting element with low drivevoltage can be manufactured.

The carbazole compound of one embodiment of the present invention has awide band gap, and thus can be favorably used as a host material of aphosphorescent material.

Example 17

In this example, a manufacturing method of a light-emitting element ofone embodiment of the present invention and measurement results ofelement characteristics thereof will be described.

A manufacturing method of a light-emitting element 11 of this examplewill be described below. FIG. 29 illustrates the element structure ofthe light-emitting element manufactured in this example. A structuralformula of an organic compound used in this example is shown below. Notethat the description of the structural formulae shown in the aboveexamples is omitted.

(Light-Emitting Element 11)

In the light-emitting element 11, the first electrode 1101, theelectron-injection layer 1115, and the second electrode 1103 were formedin manners similar to that of the light-emitting element 1 in Example 9.

In the light-emitting element 11,4-phenyl-4′-(9-phenylfluoren-9-yl)triphenylamine (abbreviation: BPAFLP)and molybdenum(VI) oxide were co-evaporated on the first electrode 1101to form the hole-injection layer 1111. The thickness of thehole-injection layer 1111 was 50 nm. The weight ratio of BPAFLP tomolybdenum(VI) oxide was adjusted to be 4:2 (=BPAFLP: molybdenum oxide).Note that the co-evaporation method refers to an evaporation method inwhich evaporation is carried out from a plurality of evaporation sourcesat the same time in one treatment chamber.

Next, BPAFLP was deposited to a thickness of 10 nm on the hole-injectionlayer 1111 to form the hole-transport layer 1112.

The light-emitting layer 1113 was formed by co-evaporation of mPCzPTpsynthesized in Example 5 andtris(2-phenylpyridinato-N,C^(2′))iridium(III) (abbreviation: Ir(ppy)₃).The weight ratio of mPCzPTp to Ir(ppy)₃ was adjusted to be 1:0.08(=mPCzPTp: Ir(ppy)₃). The thickness of the light-emitting layer 1113 was40 nm.

Next, the first electron-transport layer 1114 a was formed on thelight-emitting layer 1113 by evaporation of mPCzPTp. The thickness ofthe first electron-transport layer 1114 a was 10 nm.

Then, bathophenanthroline (abbreviation: BPhen) was deposited to athickness of 20 nm on the first electron-transport layer 1114 a to forma second electron-transport layer 1114 b.

Table 18 shows the element structure of the light-emitting element 11obtained as described above.

TABLE 18 Light-Emitting Element 11 First Electrode ITSO 1101 110 nm Hole-injection Layer BPAFLP:MoOx 1111 (=4:2) 50 nm Hole-transport layerBPAFLP 1112 10 nm Light-emitting layer mPCzPTp: 1113 Ir(ppy)3 (=1:0.08)40 nm Electron-transport 1114a mPCzPTp layer 10 nm 1114b BPhen 20 nmElectron-injection layer LiF 1115  1 nm Second Electrode Al 1103 200 nm *The mixture ratios are all represented in weight ratios.

In a glove box containing a nitrogen atmosphere, the light-emittingelement 11 was sealed so as not to be exposed to the air. After that,the operating characteristics of the light-emitting element weremeasured. Note that the measurement was carried out at room temperature(in an atmosphere kept at 25° C.).

Table 19 shows the voltage (V), current density (mA/cm²), CIEchromaticity coordinates (x,y), luminance (cd/m²), current efficiency(cd/A), power efficiency (lm/W), and external quantum efficiency (%) ofthe light-emitting element 11 at a luminance of about 1000 cd/m².

TABLE 19 Light-Emitting Element 11 Voltage (V) 5.2 Current density(mA/cm²) 1.7 Chromaticity coordinates (0.33, 0.61) (x, y) Luminance(cd/m²) 870 Current efficiency (cd/A) 52 Power efficiency (lm/W) 32External quantum 15 efficiency (%)

FIG. 66 shows the emission spectrum of the light-emitting element 11. InFIG. 66, the horizontal axis represents the wavelength (nm) and thevertical axis represents the emission intensity (arbitrary unit). FIG.67 and FIG. 68 respectively show the voltage-luminance characteristicsand the luminance-power efficiency characteristics of the light-emittingelement 11. In FIG. 67, the vertical axis represents the luminance(cd/m²) and the horizontal axis represents the voltage (V). In FIG. 68,the vertical axis represents the current efficiency (cd/A) and thehorizontal axis represents the luminance (cd/m²).

According to FIG. 66, the emission spectrum of the light-emittingelement 11 has a peak around 515 nm. The CIE chromaticity coordinate inTable 19 also shows that the light-emitting element 11 exhibits greenphosphorescence emission originating from Ir(ppy)₃ and that all theelements have excellent carrier balance. Further, in the light-emittingelement 11, the carbazole compound according to one embodiment of thepresent invention is used as a host material of a phosphorescentcompound which emits green light, and the T1 level of the carbazolecompound according to one embodiment of the present invention wasconfirmed to be sufficiently high (higher than the T1 level of at leasta phosphorescent compound which emits green light).

Further, in the light-emitting element 11 of this example, the carbazolecompound according to one embodiment of the present invention is used asan electron-transport material, and the carbazole compound according toone embodiment of the present invention was confirmed to be a materialwith an excellent electron-transport property.

Further, FIG. 67, FIG. 68, and Table 19 show that the light-emittingelement 11 has high efficiency.

As described above, the carbazole compound of one embodiment of thepresent invention is used as a material of a light-emitting element,whereby the light-emitting element can have high efficiency. Thecarbazole compound of one embodiment of the present invention has a wideband gap, and thus can be used favorably as a host material of aphosphorescent material.

Example 18

In this example, manufacturing methods of light-emitting elements of oneembodiment of the present invention and measurement results of elementcharacteristics thereof will be described.

Manufacturing methods of a light-emitting element 12 and alight-emitting element 13 will be described below. Note that elementstructures of the light-emitting elements manufactured in this exampleare similar to that in FIG. 29. A structural formula of an organiccompound used in this example is shown below. Note that the descriptionof the organic compounds whose structural formulae have already beenshown is omitted.

(Light-Emitting Element 12)

In the light-emitting element 12, the first electrode 1101, theelectron-injection layer 1115, and the second electrode 1103 were formedin a manner similar to that of the light-emitting element 1 in Example9.

In the light-emitting element 12,3-[4-(1-naphthyl)-phenyl]-9-phenyl-9H-carbazole (abbreviation: PCPN)synthesized in Example 1 and molybdenum(VI) oxide were co-evaporated onthe first electrode 1101 to form the hole-injection layer 1111. Thethickness of the hole-injection layer 1111 was 40 nm. The weight ratioof PCPN to molybdenum(VI) oxide was adjusted to be 4:2 (=PCPN:molybdenum oxide). Note that the co-evaporation method refers to anevaporation method in which evaporation is carried out from a pluralityof evaporation sources at the same time in one treatment chamber.

Next, PCPN was deposited to a thickness of 20 nm on the hole-injectionlayer 1111 to form the hole-transport layer 1112.

The light-emitting layer 1113 was formed by co-evaporation of2-[3-(dibenzothiophen-4-yl)phenyl]dibenzo[f,h]quinoxaline (abbreviation:2mDBTPDBq-II) and(dipivaloylmethanato)bis(3,5-dimethyl-2-phenylpyrazinato)iridium(III)(abbreviation: Ir(mppr-Me)₂dpm). The weight ratio of 2mDBTPDBq-II toIr(mppr-Me)₂dpm was adjusted to be 1:0.05 (=2mDBTPDBq-II:Ir(mppr-Me)₂dpm). The thickness of the light-emitting layer 1113 was 30nm.

Next, the first electron-transport layer 1114 a was formed on thelight-emitting layer 1113 by evaporation of 2mDBTPDBq-II. The thicknessof the first electron-transport layer 1114 a was 10 nm.

Then, bathophenanthroline (abbreviation: BPhen) was deposited to athickness of 20 nm on the first electron-transport layer 1114 a to forma second electron-transport layer 1114 b.

(Light-Emitting Element 13)

The light-emitting element 13 was manufactured in a manner similar tothat of the above light-emitting element 12 except for thelight-emitting layer 1113.

In the light-emitting element 13, the light-emitting layer 1113 wasformed by co-evaporation of 2mDBTPDBq-II, PCPN, and Ir(mppr-Me)₂dpm. Theweight ratio of 2mDBTPDBq-II to PCPN and Ir(mppr-Me)₂dpm was adjusted to0.7:0.3:0.05 (=2mDBTPDBq-III: PCPN: Ir(mppr-Me)₂dpm). The thickness ofthe light-emitting layer 1113 was 30 nm.

Table 20 shows the element structures of the light-emitting element 12and the light-emitting element 13 that were obtained as described above.

TABLE 20 Light-Emitting Light-Emitting Element 12 Element 13 FirstElectrode ITSO ITSO 1101 110 nm  110 nm  Hole-injection Layer PCPN:MoOxPCPN:MoOx 1111 (=4:2) (=4:2) 40 nm 40 nm Hole-transport layer PCPN PCPN1112 20 nm 20 nm Light-emitting layer 2mDBTPDBq- II: 2mDBTPDBq -II: 1113Ir(mppr-Me)2dpm PCPN: (=1:0.05) Ir(mppr-Me)2dpm (=0.7:0.3:0.05) 30 nm 30nm Electron-transport 1114a 2mDBTPDBq -II 2mDBTPDBq- II layer 10 nm 10nm 1114b BPhen BPhen 20 nm 20 nm Electron-injection layer LiF LiF 1115 1 nm  1 nm Second Electrode Al Al 1103 200 nm  200 nm  *The mixtureratios are all represented in weight ratios.

In a glove box containing a nitrogen atmosphere, the light-emittingelement 12 and the light-emitting element 13 were sealed so as not to beexposed to the air. After that, the operating characteristics of theseelements were measured. Note that the measurement was carried out atroom temperature (in an atmosphere kept at 25° C.).

Note that the light-emitting element 12 and the light-emitting element13 were formed over the same substrate. In addition, in the above twolight-emitting elements, the respective components other than thelight-emitting layer 1113 were formed at the same time, and theoperating characteristics of the two light-emitting elements weremeasured at the same time.

Table 21 shows the voltage (V), current density (mA/cm²), CIEchromaticity coordinates (x,y), luminance (cd/m²), current efficiency(cd/A), power efficiency (lm/W), and external quantum efficiency (%) ofeach of the light-emitting element 12 and the light-emitting element 13at a luminance of about 1000 cd/m².

TABLE 21 Light-Emitting Light-Emitting Element 12 Element 13 Voltage (V)2.9 3.0 Current density (mA/cm²) 2.1 1.8 Chromaticity coordinates (0.53,0.47) (0.52, 0.47) (x, y) Luminance (cd/m²) 1200 1200 Current efficiency(cd/A) 59 66 Power efficiency (lm/W) 64 69 External quantum 21 23efficiency (%)

FIG. 69 shows the emission spectra of the light-emitting element 12 andthe light-emitting element 13. In FIG. 69, the horizontal axisrepresents the wavelength (nm) and the vertical axis represents theemission intensity (arbitrary unit). FIG. 70, FIG. 71, and FIG. 72respectively show the voltage-luminance characteristics, theluminance-current efficiency, and the luminance-power efficiencycharacteristics of the light-emitting element 12 and the light-emittingelement 13. In FIG. 70, the vertical axis represents the luminance(cd/m²) and the horizontal axis represents the voltage (V). In FIG. 71,the vertical axis represents the current efficiency (cd/A) and thehorizontal axis represents the luminance (cd/m²). In FIG. 72, thevertical axis represents power efficiency (lm/W) and the horizontal axisrepresents the luminance (cd/m²).

According to FIG. 69, the emission spectra of the light-emitting element12 and the light-emitting element 13 have a peak around 580 nm. The CIEchromaticity coordinate in Table 21 also shows that the light-emittingelement 12 and the light-emitting element 13 exhibit orangephosphorescence emission originating from Ir(mppr-Me)₂dpm and that thelight-emitting elements have excellent carrier balance. Further, in thelight-emitting element 13 of this example, the carbazole compoundaccording to one embodiment of the present invention is used as a hostmaterial of a phosphorescent compound which emits orange light, and theT1 level of the carbazole compound according to one embodiment of thepresent invention was confirmed to be sufficiently high (higher than theT1 level of at least a phosphorescent compound which emits orangelight). In addition, it was found that the elements are both driven atlow voltage.

Further, FIG. 70, FIG. 71, FIG. 72, and Table 21 show that thelight-emitting element 12 and the light-emitting element 13 have highefficiency.

As described above, the carbazole compound of one embodiment of thepresent invention is used as a material of a light-emitting element,whereby the light-emitting element can have high efficiency. Thecarbazole compound of one embodiment of the present invention has a wideband gap, and thus can be used favorably as a host material of aphosphorescent material.

Further, it was indicated that when the carbazole compound of oneembodiment of the present invention is used for a hole-injection layerand a hole-transport layer, a light-emitting element with low drivevoltage can be manufactured.

Reference Example

Examples of synthesis methods of the materials for the light-emittingelements, which were used in this example, will be described below.

Synthesis Example of 2mDBTPDBq-II

A synthesis method of2-[3-(dibenzothiophen-4-yl)phenyl]dibenzo[f,h]quinoxaline (abbreviation:2mDBTPDBq-II) will be described. The synthesis scheme thereof is shownin (R-1).

In a 2-L three-neck flask were put 5.3 g (20 mmol) of2-chlorodibenzo[f,h]quinoxaline, 6.1 g (20 mmol) of3-(dibenzothiophen-4-yl)phenylboronic acid, 460 mg (0.4 mmol) oftetrakis(triphenylphosphine)palladium(0), 300 mL of toluene, 20 mL ofethanol, and 20 mL of a 2M aqueous potassium carbonate solution. Themixture was deaerated by being stirred under reduced pressure, and theatmosphere in the flask was replaced with nitrogen. This mixture wasstirred under a nitrogen stream at 100° C. for 7.5 hours. After beingcooled to room temperature, the obtained mixture was filtered to give awhite substance. The substance obtained by the filtration was washedwell with water and ethanol in this order, and then dried. The obtainedsolid was dissolved in about 600 mL of hot toluene, followed by suctionfiltration through Celite and Florisil, whereby a clear colorlessfiltrate was obtained. The obtained filtrate was concentrated andpurified by silica gel column chromatography. The chromatography wascarried out using toluene at a temperature of about 40° C. as adeveloping solvent. Acetone and ethanol were added to the solid obtainedhere, followed by irradiation with ultrasonic waves. Then, the generatedsuspended solid was filtrated and the obtained solid was dried to give7.85 g of white powder that was the objective substance in a yield of80%.

The above objective substance was relatively soluble in hot toluene, butis easily precipitated when cooled. Further, the substance was poorlysoluble in other organic solvents such as acetone and ethanol. Thus, theutilization of these different degrees of solubility resulted in ahigh-yield synthesis by a simple method as above. Specifically, afterthe reaction finished, the mixture was returned to room temperature andthe precipitated solid was collected by filtration, whereby mostimpurities were able to be easily removed. Further, by the columnchromatography using hot toluene as a developing solvent, the generatedsubstance, which was easily precipitated, was able to be readilypurified.

By a train sublimation method, 4.0 g of the obtained white powder wassublimated and purified. In the sublimation purification, the whitepowder was heated at 300° C. under a pressure of 5.0 Pa with a flow rateof argon gas of 5 mL/min. After the sublimation purification, 3.5 g ofwhite powder that was the objective substance was obtained in a yield of88%.

A nuclear magnetic resonance (NMR) method identified this compound as2-[3-(dibenzothiophen-4-yl)phenyl]dibenzo[f,h]quinoxaline (abbreviation:2mDBTPDBq-II) that was the objective substance.

¹H NMR data of the obtained substance is shown below.

¹H NMR (CDCl₃, 300 MHz): δ (ppm)=7.45-7.52 (m, 2H), 7.59-7.65 (m, 2H),7.71-7.91 (m, 7H), 8.20-8.25 (m, 2H), 8.41 (d, J=7.8 Hz, 1H), 8.65 (d,J=7.5 Hz, 2H), 8.77-8.78 (m, 1H), 9.23 (dd, J=7.2 Hz, 1.5 Hz, 1H), 9.42(dd, J=7.8 Hz, 1.5 Hz, 1H), 9.48 (s, 1H).

Synthesis Example of Ir(mppr-Me)₂dpm

A synthesis method of(dipivaloylmethanato)bis(3,5-dimethyl-2-phenylpyrazinato)iridium(III)(abbreviation: Ir(mppr-Me)₂dpm) will be described. The synthesis schemethereof is shown in (R-2).

First, 20 mL of 2-ethoxyethanol, 1.55 g of a binuclear complexdi-μ-chloro-bis[bis(3,5-dimethyl-2-phenylpyrazinato)iridium(III)](abbreviation: [Ir(mppr-Me)₂Cl]₂), 0.8 ml of dipivaloylmethane, and 1.38g of sodium carbonate were mixed. The mixture was irradiated withmicrowaves under argon bubbling for 30 minutes to be reacted. After thereaction, the reaction solution was cooled down to room temperature, andwater was added thereto. This mixture solution was separated into anorganic layer and an aqueous layer, and the aqueous layer was subjectedto extraction with dichloromethane. The organic layer was combined withthe solution of the extract, the mixture was washed with water, followedby drying with anhydrous magnesium sulfate. After that, the mixture wasgravity-filtered, and the filtrate was concentrated to be dried andhardened. This solid was recrystallized from a mixed solvent ofdichloromethane and ethanol to give red powder in a yield of 67%. Notethat the irradiation with microwaves was performed using a microwavesynthesis system (Discover, manufactured by CEM Corporation).

Note that a nuclear magnetic resonance (NMR) method identified thiscompound as an organometallic complex [Ir(mppr-Me)₂dpm] that was theobjective substance. ¹H NMR data of the obtained compound is shownbelow.

¹H NMR. δ (CDCl₃): 0.90 (s, 1H), 2.59 (s, 6H), 3.04 (s, 6H), 5.49 (s,1H), 6.32 (dd, 2H), 6.70 (dt, 2H), 6.88 (dt, 2H), 7.86 (d, 2H), 8.19 (s,2H).

Example 19

In this example, manufacturing methods of light-emitting elements of oneembodiment of the present invention and measurement results of elementcharacteristics thereof will be described.

Hereinafter, manufacturing methods of light-emitting elements 14 to 17will be described. Note that element structures of the light-emittingelements manufactured in this example are the same as that in FIG. 29. Astructural formula of an organic compound used in this example is shownbelow. Note that the description of the organic compounds whosestructural formulae have already been shown is omitted.

(Light-Emitting Element 14)

The light-emitting element 14 was manufactured in a manner similar tothat of the light-emitting element 12 in Example 18 except for thelight-emitting layer 1113.

In the light-emitting element 14, the light-emitting layer 1113 wasformed by co-evaporation of2-[3-(dibenzothiophen-4-yl)phenyl]dibenzo[f,h]quinoxaline (abbreviation:2mDBTPDBq-II),4,4′-di(1-naphthyl)-4″-(9-phenyl-9H-carbazol-3-yl)triphenylamine(abbreviation: PCBNBB), and(dipivaloylmethanato)bis(3,5-dimethyl-2-phenylpyrazinato)iridium(III)(abbreviation: Ir(mppr-Me)₂dpm). The weight ratio of 2mDBTPDBq-II toPCBNBB and Ir(mppr-Me)₂dpm was adjusted to 0.8:0.2:0.05 (=2mDBTPDBq-II:PCBNBB: Ir(mppr-Me)₂dpm). The thickness of the light-emitting layer 1113was 40 nm.

(Light-Emitting Element 15)

The light-emitting element 15 was manufactured in a manner similar tothat of the above light-emitting element 14 except for thehole-injection layer 1111 and the hole-transport layer 1112.

In the light-emitting element 15, the hole-injection layer 1111 wasformed in such a manner that3-[4-(9-phenanthryl)-phenyl]-9-phenyl-9H-carbazole (abbreviation: PCPPn)synthesized in Example 2 and molybdenum(VI) oxide were co-evaporated onthe first electrode 1101. The thickness of the hole-injection layer 1111was 40 nm. The weight ratio of PCPPn to molybdenum(VI) oxide wasadjusted to 4:2 (=PCPPn: molybdenum oxide).

Next, PCPPn was deposited to a thickness of 20 nm on the hole-injectionlayer 1111 to form the hole-transport layer 1112.

(Light-Emitting Element 16)

The light-emitting element 16 was manufactured in a manner similar tothat of the above light-emitting element 14 except for thehole-injection layer 1111.

In the light-emitting element 16, the hole-injection layer 1111 wasformed in such a manner that9-[4-(9-phenylcarbazol-3-yl)phenyl]-10-phenylanthracene (abbreviation:PCzPA) and molybdenum(VI) oxide were co-evaporated on the firstelectrode 1101. The thickness of the hole-injection layer 1111 was 40nm. The weight ratio of PCzPA to molybdenum(VI) oxide was adjusted to be4:2 (=PCzPA: molybdenum oxide).

(Light-Emitting Element 17)

The light-emitting element 17 was manufactured in a manner similar tothat of the above light-emitting element 15 except for thehole-injection layer 1111. The hole-injection layer 1111 of thelight-emitting element 17 was manufactured in a manner similar to thatof the above light-emitting element 16.

Table 22 shows the element structures of the light-emitting elements 14to 17 manufactured as described above.

TABLE 22 Light-Emitting Light-Emitting Light-Emitting Light-EmittingElement 14 Element 15 Elementt 16 Element 17 First Electrode ITSO ITSOITSO ITSO 1101 110 nm  110 nm  110 nm  110 nm  Hole-injection LayerPCPN:MoOx PCPPn:MoOx PCzPA:MoOx PCzPA:MoOx 1111 (=4:2) (=4:2) (=4:2)(=4:2) 40 nm 40 nm 40 nm 40 nm Hole-transport layer PCPN PCPPn PCPNPCPPn 1112 20 nm 20 nm 20 nm 20 nm Light-emitting layer 2mDBTPDBq-II:2mDBTPDBq-II: 2mDBTPDBq- II: 2mDBTPDBq-II: 1113 CBNBB: CBNBB: CBNBB:CBNBB: Ir(mppr-Me)2dpm Ir(mppr-Me)2dpm Ir(mppr-Me)2dpm Ir(mppr-Me)2dpm(=0.8:0.2:0.05) (=0.8:0.2:0.05) (=0.8:0.2:0.05) (=0.8:0.2:0.05) 40 nm 40nm 40 nm 40 nm Electron-transport 1114a 2mDBTPDBq -II 2mDBTPDBq -II2mDBTPDBq -II 2mDBTPDBq -II layer 10 nm 10 nm 10 nm 10 nm 1114b BPhenBPhen BPhen BPhen 20 nm 20 nm 20 nm 20 nm Electron-injection layer LiFLiF LiF LiF 1115  1 nm  1 nm  1 nm  1 nm Second Electrode Al Al Al Al1103 200 nm  200 nm  200 nm  200 nm  *The mixture ratios are allrepresented in weight ratios.

In a glove box containing a nitrogen atmosphere, the light-emittingelements 14 to 17 were sealed so as not to be exposed to the air. Afterthat, the operating characteristics of these elements were measured.Note that the measurement was carried out at room temperature (in anatmosphere kept at 25° C.).

Note that the light-emitting elements 14 to 17 were formed over the samesubstrate. In addition, in the above four light-emitting elements, thecomponents other than the hole-injection layers 1111 and thehole-transport layers 1112 were formed at the same time, and measurementof the operating characteristics of the four light-emitting elementswere performed at the same time.

Table 23 shows the voltage (V), current density (mA/cm²), CIEchromaticity coordinates (x,y), luminance (cd/m²), current efficiency(cd/A), power efficiency (lm/W), and external quantum efficiency (%) ofeach of the light-emitting elements 14 to 17 at a luminance of about1000 cd/m².

TABLE 23 Light-Emitting Light-Emitting Light-Emitting Light-EmittingElement 14 Element 15 Element 16 Element 17 Voltage (V) 2.8 2.9 2.8 2.9Current density (mA/cm²) 1.5 1.8 1.5 1.9 Chromaticity coordinates (0.52,0.47) (0.52, 0.47) (0.52, 0.47) (0.52, 0.47) (x, y) Luminance (cd/m²)1050 1200 980 1200 Current efficiency (cd/A) 68 68 65 66 Powerefficiency (lm/W) 77 74 73 71 External quantumefficiency (%) 24 24 23 23

FIG. 73 shows the emission spectra of the light-emitting elements 14 to17. In FIG. 73, the horizontal axis represents the wavelength (nm) andthe vertical axis represents the emission intensity (arbitrary unit).FIG. 74, FIG. 75, and FIG. 76 respectively show the voltage-luminancecharacteristics, the luminance-current efficiency characteristics, andthe luminance-power efficiency characteristics of the light-emittingelements 14 to 17. FIG. 74, the vertical axis represents the luminance(cd/m²) and the horizontal axis represents the voltage (V). In FIG. 75,the vertical axis represents the current efficiency (cd/A) and thehorizontal axis represents the luminance (cd/m²). In FIG. 76, thevertical axis represents the power efficiency (lm/W) and the horizontalaxis represents the luminance (cd/m²).

According to FIG. 73, the light-emitting elements 14 to 17 have peaksaround 580 nm. The CIE chromaticity coordinates in Table 23 also showthat the light-emitting elements 14 to 17 exhibit orange phosphorescenceemission originating from Ir(mppr-Me)₂dpm and that all the elements haveexcellent carrier balance.

Further, FIG. 74, FIG. 75, FIG. 76, and Table 23 show that thelight-emitting elements 14 to 17 have high efficiency.

Further, it was also found that the light-emitting elements 14 and 15 ineach of which the layer containing the carbazole compound of oneembodiment of the present invention is used for the hole-injection layer1111 have higher efficiency than the light-emitting elements 16 and 17.In addition, it was found that the light-emitting elements 14 and 15 canbe driven at a voltage as low as that of the comparative light-emittingelements 16 and 17.

Further, a reliability test was conducted on the manufacturedlight-emitting elements 14 to 17. In the reliability test, the initialluminance was set at 5000 cd/m², these elements were operated at aconstant current density, and the luminance was measured at regularintervals. The results obtained by the reliability test are shown inFIG. 77. In FIG. 77, the horizontal axis represents the current flowtime (hour) and the vertical axis represents the percentage of luminanceto the initial luminance at each time, that is, normalized luminance(%).

As shown in FIG. 77, a reduction in the luminance of each of thelight-emitting elements 14 to 17 with time does not easily occur and thelifetime of each of the elements is long. The light-emitting elements14, 15, 16, and 17 respectively maintained 87%, 83%, 81%, and 79% of theinitial luminance even after being driven for 190 hours.

As described above, the carbazole compound of one embodiment of thepresent invention is used as a material for a light-emitting element,whereby the light-emitting element can have high efficiency.

Further, it was indicated that when the carbazole compound of oneembodiment of the present invention is used for a hole-injection layerand a hole-transport layer, a light-emitting element with low drivevoltage can be manufactured.

Further, it was indicated that when the carbazole compound of oneembodiment of the present invention is used for a hole-injection layerand a hole-transport layer, a light-emitting element with long lifetimecan be manufactured.

Example 20

In this example, manufacturing methods of light-emitting elements eachof which is one embodiment of the present invention and measurementresults of element characteristics thereof will be described togetherwith measurement results of a comparative light-emitting element.

Manufacturing methods of a light-emitting element 18, a light-emittingelement 19, and a comparative light-emitting element 9 of this examplewill be described below. Note that element structures of thelight-emitting elements manufactured in this example are similar to thatin FIG. 62. In addition, organic compounds used in this example are theones whose structural formulae have already been shown; therefore, thedescription thereof is omitted.

(Light-Emitting Element 18)

The light-emitting element 18 was manufactured in a manner similar tothat of the above light-emitting element 8 in Example 14 except for thehole-injection layer 1111, the hole-transport layer 1112, and thelight-emitting layer 1113.

In the light-emitting element 18, the hole-injection layer 1111 wasformed in such a manner that PCPN synthesized in Example 1 andmolybdenum(VI) oxide were co-evaporated on the first electrode 1101. Thethickness of the hole-injection layer 1111 was 50 nm. The weight ratioof PCPN to molybdenum(VI) oxide was adjusted to be 4:2 (=PCPN:molybdenum oxide).

Next, PCPN was deposited to a thickness of 10 nm on the hole-injectionlayer 1111 to form the hole-transport layer 1112.

In the light-emitting element 18, the first light-emitting layer 1113 aand the second light-emitting layer 1113 b were stacked in this order onthe first electrode 1101 to form the light-emitting layer 1113.

The first light-emitting layer 1113 a was formed by co-evaporation ofPCPN and 1,6FLPAPrn. The weight ratio of PCPN to 1,6FLPAPrn was adjustedto be 1:0.05 (=PCPN: 1,6FLPAPrn). The thickness of the firstlight-emitting layer 1113 a was 10 nm.

The second light-emitting layer 1113 b was formed by co-evaporation ofCzPA and 1,6FLPAPrn. The weight ratio of CzPA to 1,6FLPAPrn was adjustedto be 1:0.05 (=CzPA: 1,6FLPAPrn). The thickness of the secondlight-emitting layer 1113 b was 25 nm.

(Light-Emitting Element 19)

The light-emitting element 19 was manufactured in a manner similar tothat of the above light-emitting element 18 except for thehole-injection layer 1111, the hole-transport layer 1112, and the firstlight-emitting layer 1113 a.

In the light-emitting element 19, the hole-injection layer 1111 wasformed in such a manner that PCPPn synthesized in Example 2 andmolybdenum(VI) oxide were co-evaporated on the first electrode 1101. Thethickness of the hole-injection layer 111 was 50 nm. The weight ratio ofPCPPn to molybdenum(VI) oxide was adjusted to be 4:2 (=PCPPn: molybdenumoxide).

Next, PCPPn was deposited to a thickness of 10 nm on the hole-injectionlayer 1111 to form the hole-transport layer 1112.

In the light-emitting element 19, the first light-emitting layer 1113 awas formed by co-evaporation of PCPPn and 1,6FLPAPrn. The weight ratioof PCPN to 1,6FLPAPrn was adjusted to be 1:0.05 (=PCPPn: 1,6FLPAPrn).The thickness of the first light-emitting layer 1113 a was 10 nm.

(Comparative Light-Emitting Element 9)

The comparative light-emitting element 9 was manufactured in a mannersimilar to that of the light-emitting element 18 except for thehole-injection layer 1111, the hole-transport layer 1112, and the firstlight-emitting layer 1113 a.

In the comparative light-emitting element 9, the hole-injection layer1111 was formed in such a manner that PCzPA and molybdenum(VI) oxidewere co-evaporated on the first electrode 1101. The thickness of thehole-injection layer 1111 was 50 nm. The weight ratio of PCzPA tomolybdenum(VI) oxide was adjusted to be 4:2 (=PCzPA: molybdenum oxide).

Next, PCzPA was deposited to a thickness of 10 nm on the hole-injectionlayer 1111 to form the hole-transport layer 1112.

In the comparative light-emitting element 9, the first light-emittinglayer 1113 a was formed by co-evaporation of PCzPA and 1,6FLPAPrn. Theweight ratio of PCzPA to 1,6FLPAPrn was adjusted to be 1:0.05 (=PCzPA:1,6FLPAPrn). The thickness of the first light-emitting layer 1113 a was10 nm.

Table 24 shows the element structures of the light-emitting elements 18and 19 and the comparative light-emitting element 9 that weremanufactured as described above.

TABLE 24 Light-Emitting Light-Emitting Comparative Light- Element 18Element 19 Emitting Element 9 First Electrode ITSO ITSO ITSO 1101 110nm  110 nm  110 nm  Hole-injection Layer PCPN:MoOx PCPPn:MoOx PCzPA:MoOx1111 (=4:2) (=4:2) (=4:2) 50 nm 50 nm 50 nm Hole-transport layer PCPNPCPPn PCzPA 1112 10 nm 10 nm 10 nm Light-Emitting Layer 1113a PCPN:PCPPn: PCzPA: 1113 1,6FLPAPrn 1,6FLPAPrn 1,6FLPAPrn (=1:0.05) (=1:0.05)(=1:0.05) 10 nm 10 nm 10 nm 1113b CzPA: CzPA: CzPA: 1,6FLPAPrn1,6FLPAPrn 1,6FLPAPrn (=1:0.05) (=1:0.05) (=1:0.05) 25 nm 25 nm 25 nmElectron-transport 1114a Alq Alq Alq layer 10 nm 10 nm 10 nm 1114b BPhenBPhen BPhen 15 nm 15 nm 15 nm Electron-injection layer LiF LiF LiF 1115 1 nm  1 nm  1 nm Second Electrode Al Al Al 1103 200 nm  200 nm  200 nm *The mixture ratios are all represented in weight ratios.

In a glove box containing a nitrogen atmosphere, the light-emittingelements 18 and 19 and the comparative light-emitting element 9 weresealed so as not to be exposed to the air. After that, the operatingcharacteristics of these elements were measured. Note that themeasurement was carried out at room temperature (in an atmosphere keptat 25° C.).

Note that the light-emitting elements 18 and 19 and the comparativelight-emitting element 9 were formed over the same substrate. Inaddition, in the above three light-emitting elements, the componentsother than the hole-injection layers 1111, the hole-transport layers1112, and the first light-emitting layer 1113 a were formed at the sametime, and the three light-emitting elements were operated at the sametime.

Table 25 shows the voltage (V), current density (mA/cm²), CIEchromaticity coordinates (x,y), luminance (cd/m²), current efficiency(cd/A), power efficiency (lm/W), and external quantum efficiency (%) ofeach of the light-emitting elements 18 and 19 and the comparativelight-emitting element 9 at a luminance of about 1000 cd/m².

TABLE 25 Light-Emitting Light-Emitting Comparative Light- Element 18Element 19 Emitting Element 9 Voltage (V) 4.6 4.4 4.4 Current density(mA/cm²) 8.5 7.6 12 Chromaticity coordinates (0.15, 0.20) (0.15, 0.21)(0.15, 0.19) (x, y) Luminance (cd/m²) 920 810 1000 Current efficiency(cd/A) 11 11 9 Power efficiency (lm/W) 7.4 7.6 6.1 External quantum 8.07.4 6.5 efficiency (%)

FIG. 78 shows the emission spectra of the light-emitting elements 18 and19 and the comparative light-emitting element 9. In FIG. 78, thehorizontal axis represents the wavelength (nm) and the vertical axisrepresents the emission intensity (arbitrary unit). FIG. 79, FIG. 80,and FIG. 81 respectively show the voltage-luminance characteristics, theluminance-current efficiency characteristics, and the luminance-powerefficiency characteristics of the light-emitting elements 18 and 19 andthe comparative light-emitting element 9. FIG. 79, the vertical axisrepresents the luminance (cd/m²) and the horizontal axis represents thevoltage (V). In FIG. 80, the vertical axis represents the currentefficiency (cd/A) and the horizontal axis represents the luminance(cd/m²). In FIG. 81, the vertical axis represents the power efficiency(lm/W) and the horizontal axis represents the luminance (cd/m²).

According to FIG. 78, all of the light-emitting elements 18 and 19 andthe comparative light-emitting element 9 have peaks around 470 nm. TheCIE chromaticity coordinates in Table 25 also show that thelight-emitting elements 18 and 19 and the comparative light-emittingelement 9 exhibit blue light emission originating from 1,6FLPAPrn andthat the elements have excellent carrier balance. Further, in thelight-emitting elements 18 and 19, the carbazole compound according toone embodiment of the present invention is used as a host material of afluorescent compound which emits blue fluorescence, and the S1 level ofthe carbazole compound according to one embodiment of the presentinvention was confirmed to be sufficiently high (higher than the S1level of at least a fluorescent compound which emits blue light).

In particular, the light-emitting elements 18 and 19 in each of whichthe carbazole compound according to one embodiment of the presentinvention is used in the first light-emitting layer 1113 a have higherefficiency than the comparative light-emitting element 9. This showsthat the S1 level of the carbazole compound according to one embodimentof the present invention is sufficiently high.

Further, FIG. 79, FIG. 80, FIG. 81, and Table 25 show that thelight-emitting elements 18 and 19 can be driven at a voltage as low asthat of the comparative light-emitting element 9 and that thelight-emitting elements 18 and 19 have higher efficiency than thecomparative light-emitting element 9. The reason for the above isprobably as follows. The band gap of the carbazole compound of oneembodiment of the present invention, which is used in the light-emittingelements 18 and 19 in this example, is wider than the band gap of PCzPAused in the comparative light-emitting element 9; thus, energy transferfrom the light-emitting layer can be efficiently suppressed in the casewhere the carbazole compound is used as a material of the hole-transportlayer in contact with the light-emitting layer. The LUMO level (absolutevalue) of the carbazole compound of one embodiment of the presentinvention, which is used in the light-emitting elements 18 and 19 inthis example, is shallower (smaller) than the LUMO level of PCzPA usedin the comparative light-emitting element 9; thus, loss of carriers dueto leakage of electrons from the light-emitting layer can be suppressed.Moreover, the HOMO level (absolute value) of the carbazole compound ofone embodiment of the present invention, which is used in thelight-emitting elements 18 and 19 in this example, is deeper (larger)than the HOMO level of PCzPA used in the comparative light-emittingelement 9; thus, injection of holes into the light-emitting layer can beperformed efficiently.

Further, it was found that the light-emitting elements both can bedriven at a voltage as low as that of the comparative light-emittingelement and that the light-emitting elements both have good transfer ofcarriers. This shows that the carrier-transport property of thecarbazole compound according to one embodiment of the present inventionis excellent.

As described above, the carbazole compound of one embodiment of thepresent invention is used as a material of a light-emitting element,whereby the light-emitting element can have high efficiency. Inaddition, the carbazole compound of one embodiment of the presentinvention can be used as a host material of a blue fluorescent material.

Example 21

In this example, an example of producing9-phenyl-9H-3-{[3,5-di(phenanthren-9-yl)phenyl]phenyl}carbazole(abbreviation: Pn2BPPC) that is a carbazole compound of one embodimentof the present invention, in which R¹ is a phenyl group, R² is hydrogen,α³ is a biphenyldiyl group having a phenanthrenyl group as asubstituent, and Ar³ is a phenanthrenyl group in General Formula (G1)will be described.

Step 1: Synthesis Method of9-[3-chloro-5-(phenanthren-9-yl)phenyl]phenanthrene (abbreviation:Cl-PPn2)

In a 200-mL three-neck flask, a mixture of 2.90 g (10.7 mmol) of1,3-dibromo-5-chlorobenzene, 5.0 g (22.5 mmol) of 9-phenanthrene boronicacid, 50.6 mg (0.23 mmol) of palladium(II) acetate, 207 mg (0.68 mmol)of tri(o-tolyl)phosphine, 70 mL of toluene, 7 mL of ethanol, and 20 mLof a potassium carbonate aqueous solution (2 mol/L) was deaerated whilebeing stirred under reduced pressure and was heated and stirred in anitrogen atmosphere at 85° C. for 6 hours to be reacted. In addition,50.6 mg (0.23 mmol) of palladium(II) acetate and 207 mg (0.68 mmol) oftri(o-tolyl)phosphine were added to the mixture, and the mixture washeated and stirred in a nitrogen atmosphere at 85° C. for 7.5 hours, andthen heated and stirred at 110° C. for 7.5 hours to be reacted.

After reaction, 300 mL of toluene was added to the reaction mixturesolution, and an organic layer of the mixture solution was filtratedthrough Florisil (produced by Wako Pure Chemical Industries, Ltd.,Catalog No. 540-00135), alumina (neutral, produced by Merck Ltd), andCelite (produced by Wako Pure Chemical Industries, Ltd., Catalog No.531-16855). The obtained filtrate was washed with water, and magnesiumsulfate was added thereto so that moisture was adsorbed. This suspensionwas filtrated to obtain a filtrate. The obtained filtrate wasconcentrated and purified by silica gel column chromatography. At thistime, a mixed solvent of toluene and hexane (toluene: hexane=1:5) wasused as a developing solvent for the chromatography. The obtainedfraction was concentrated, and toluene and hexane were added thereto.The mixture was irradiated with ultrasonic waves and then recrystallizedto give 3.11 g of white powder that was an objective substance in ayield of 63%. The reaction scheme of the synthesis method is shown in(F8-1).

The Rf value of the objective substance was 0.25, which was obtained bysilica gel thin layer chromatography (TLC) (with a developing solventcontaining ethyl acetate and hexane in a 1:10 ratio).

The compound obtained in Step 1 was examined by a nuclear magneticresonance (NMR) method. The measurement data are shown below.

¹H NMR (CDCl₃, 300 MHz): δ (ppm)=7.59-7.73 (m, 11H), 7.79 (s, 2H), 7.92(d, J=7.81 Hz, 2H), 8.06 (d, J=8.30 Hz, 2H), 8.73 (d, J=8.30 Hz, 2H),8.79 (d, J=8.30 Hz, 2H).

FIGS. 82A and 82B are ¹H NMR charts. Note that FIG. 82B is a chartshowing an enlarged part of FIG. 82A in the range of 7.00 ppm to 9.00ppm. The measurement results confirmed that9-[3-chloro-5-(phenanthren-9-yl)phenyl]phenanthrene (abbreviation:Cl-PPn2) that was the objective substance was able to be obtained.

Step 2: Synthesis Method of9-phenyl-9H-3-{4-[3,5-di(phenanthren-9-yl)phenyl]phenyl}carbazole(abbreviation: Pn2BPPC)

In a 200-mL three-neck flask, a mixture of 1.04 g (2.87 mmol) of9-[3-chloro-5-(phenanthren-9-yl)phenyl]phenanthrene, 2.00 g (4.31 mmol)of 3-(9-phenyl-9H-carbazole)phenyl-4-boronic acid, 49.5 mg (0.09 mmol)of bis(dibenzylideneacetone)palladium(0), 91.8 mg (0.24 mmol) of2′-(dicyclohexylphosphino)acetophenone ethylene ketal, 1.31 g (8.61mmol) of cesium(I) fluoride, and 30 ml of xylene was heated and stirredin a nitrogen atmosphere at 150° C. for 12 hours to be reacted.

After reaction, 500 mL of toluene was added to the reaction mixturesolution, and the mixture solution was filtered through alumina(neutral, produced by Merck Ltd) and Celite (produced by Wako PureChemical Industries, Ltd., Catalog No. 531-16855). The obtained filtratewas concentrated and purified by silica gel column chromatography. Atthis time, a mixed solvent of toluene and hexane (toluene: hexane=1:5)was used as a developing solvent for the chromatography. The obtainedfraction was concentrated, and hexane was added thereto. The mixture wasirradiated with ultrasonic waves and then recrystallized to obtain 1.9 gof white powder that was an objective substance in a yield of 89%. Thereaction scheme of the synthesis method is shown in (F8-2).

The Rf value of the objective substance was 0.29, which was obtained bysilica gel thin layer chromatography (TLC) (with a developing solventcontaining ethyl acetate and hexane in a 1:10 ratio).

The compound obtained in Step 2 above was examined by a nuclear magneticresonance (NMR) method. The measurement data are shown.

¹H NMR (CDCl₃, 300 MHz): δ (ppm)=7.43 (d, J=3.4 Hz, 2H), 7.46-7.50 (m,2H), 7.60-7.99 (m, 25H), 8.19-8.23 (m, 3H), 8.41 (d, J=0.98 Hz, 1H),8.76 (d, J=8.30 Hz, 2H), 8.82 (d, J=7.32 Hz, 2H).

FIGS. 83A and 83B are ¹H NMR charts. Note that FIG. 83B is a chartshowing an enlarged part of FIG. 83A in the range of 7.00 ppm to 9.00ppm. The measurement results confirmed that9-phenyl-9H-3-{4-[3,5-di(phenanthren-9-yl)phenyl]phenyl}carbazole(abbreviation: Pn2BPPC) that was the objective substance was able to beobtained.

Note that although the example in which the phenanthrene compound havingchlorine as a reaction group is coupled with the carbazole compound isdescribed in this example, a phenanthrene compound having iodine orbromine as a reaction group may be used without limitation thereto. Aphenanthrene compound that can be used in Step 2 above can berepresented by General Formula (I1), for example. Note that in the casewhere the phenanthrene compound represented by General (I1) has bromineor iodine as a reaction group, Pn2BPPC (abbreviation) can be synthesizedin a manner similar to that in Step 2 above. In Step 1, in the case ofspecifically reacting phenanthrene-9-boronic acid with trihalogenatedbenzene at 2:1, it is preferable that a halogen which reacts withboronic acid have a higher reaction property than a halogen representedby X. Thus, in the case where X bonded to benzene is chlorine, halogensat the 3-position and the 5-position are preferably bromine or iodine.In the case where X bonded to benzene is bromine, the halogens at the3-position and the 5-position are preferably iodine.

Note that in General Formula (I1), X represents chlorine, bromine, oriodine.

FIG. 84A shows an absorption spectrum of synthesized Pn2BPPC in atoluene solution of Pn2BPPC, and FIG. 84B shows an emission spectrumthereof. FIG. 85A shows an absorption spectrum of a thin film ofPn2BPPC, and FIG. 85B shows an emission spectrum thereof. The absorptionspectrum was measured with an ultraviolet-visible spectrophotometer(V550, produced by JASCO Corporation). The emission spectrum wasmeasured with a fluorescence spectrophotometer (FS920, produced byHamamatsu Photonics Corporation). The measurements were performed withsamples prepared in such a manner that the solution was put in a quartzcell while the thin film was obtained by evaporation onto a quartzsubstrate. FIG. 84A show the absorption spectrum of Pn2BPPC in thesolution of Pn2BPPC which was obtained by subtracting the absorptionspectra of the quartz cell and toluene put therein. FIG. 85A shows theabsorption spectrum of the thin film which was obtained by subtractingthe absorption spectrum of the quartz substrate. In FIGS. 84A and 84Band FIGS. 85A and 85B, the horizontal axis represents wavelength (nm)and the vertical axis represents intensity (arbitrary unit). In the caseof the toluene solution, the absorption peak was observed at around 303nm, and the maximum emission wavelength was 388 nm (excitationwavelength: 340 nm). In the case of the thin film, the absorption peakwas observed at around 306 nm, and the maximum emission wavelength was417 nm (excitation wavelength: 306 nm).

The absorption spectrum showed that Pn2BPPC described in this example isa material having weak absorption of light in the visible region. Inaddition, the emission spectrum shows that Pn2BPPC exhibits blue-violetemission.

In this example, Pn2BPPC (abbreviation) of General Formula (G1) ispreferable for the following reason: a biphenyl group of α³ is bonded tothe 3-position of carbazole at the para position, which allows highreliability.

Example 22

In this example, a synthesis example of producing9-phenyl-9H-3-[3,5-di(phenanthrene-9-yl)phenyl]carbazole (abbreviation:Pn2PPC) represented by Structural Formula (197) in Embodiment 1 will bedescribed.

Step 1: Synthesis Method of 3-(3,5-dichlorophenyl)-9-phenyl-9H-carbazole(abbreviation: PCPCl₂)

In a 200-mL three-neck flask, a mixture of 5.0 g (22.1 mmol) of3-(9-phenyl-9H-carbazole)boronic acid, 7.63 g (26.6 mmol) of1-bromo-3,5-dichlorobenzene, 58.4 mg (0.26 mmol) of palladium(II)acetate, 237 mg (0.78 mmol) of tri(o-tolyl)phosphine, 98 mL of toluene,10 mL of ethanol, and 32 mL of an aqueous solution of potassiumcarbonate (2 mol/L) was deaerated while being stirred under reducedpressure and was heated and stirred in a nitrogen atmosphere at 80° C.for 7 hours to be reacted.

After reaction, 500 mL of toluene was added to the reaction solution,and an organic layer of the reaction solution was filtered throughFlorisil, alumina, and Celite. The obtained filtrate was washed withwater, and magnesium sulfate was added thereto so that moisture wasadsorbed. This suspension was filtrated to obtain a filtrate. Theobtained filtrate was concentrated and purified by silica gel columnchromatography. At this time, a mixed solvent of toluene and hexane(toluene: hexane=1:10) was used as a developing solvent for thechromatography. The obtained fraction was concentrated, and toluene andhexane were added thereto. The mixture was irradiated with ultrasonicwaves and then recrystallized to obtain 9.09 g of white powder that wasan objective substance in a yield of 100%. The reaction scheme of thesynthesis method is shown in (F9-1).

The Rf value of the objective substance was 0.43, which was obtained bysilica gel thin layer chromatography (TLC) (with a developing solventcontaining ethyl acetate and hexane in a 1:10 ratio).

The compound obtained in Step 1 was examined by a nuclear magneticresonance (NMR) method. The measurement data are shown below.

¹H NMR (CDCl₃, 300 MHz): δ (ppm)=7.26-7.34 (m, 2H), 7.40-7.53 (m, 4H),7.57-7.67 (m, 7H), 8.20 (d, J=7.81 Hz, 1H), 8.31 (d, J=0.98 Hz, 1H).

FIGS. 86A and 86B are ¹H NMR charts. Note that FIG. 86B is a chartshowing an enlarged part of FIG. 86A in the range of 7.00 ppm to 8.50ppm. The measurement results confirmed that3-(3,5-dichlorophenyl)-9-phenyl-9H-carbazole (abbreviation: PCPCl₂) thatwas the objective substance was able to be obtained.

Step 2: Synthesis Method of9-phenyl-9H-3-[3,5-di(phenanthrene-9-yl)phenyl]carbazole (abbreviation:Pn2PPC)

In a 200-mL three-neck flask, a mixture of 4.29 g (19.3 mmol) of9-phenanthrene boronic acid, 3.0 g (7.73 mmol) of3-(3,5-dichlorophenyl)-9-phenyl-9H-carbazole, 86.3 mg (0.15 mmol) ofbis(dibenzylideneacetone)palladium(0), 166 mg (0.46 mmol) of2′-(dicyclohexylphosphino)acetophenone ethylene ketal, 6.98 g (46 mmol)of cesium(I) fluoride, and 30 mL of xylene was heated and stirred in anitrogen atmosphere at 120° C. for 10 hours to be reacted. Moreover, 858mg (3.87 mmol) of 9-phenanthrene boronic acid, 86.3 mg (0.15 mmol) ofbis(dibenzylideneacetone)palladium(0), and 166 mg (0.46 mmol) of2′-(dicyclohexylphosphino)acetophenone ethylene ketal were added to themixture, and the mixture was heated and stirred in a nitrogen atmosphereat 120° C. for 8 hours to be reacted.

After reaction, 500 mL of toluene was added to the reaction mixturesolution, and an organic layer of the mixture solution was filteredthrough alumina and Celite. The obtained filtrate was washed with water,and magnesium sulfate was added thereto so that moisture was adsorbed.This suspension was filtered to obtain a filtrate. The obtained filtratewas concentrated and purified by silica gel column chromatography. Atthis time, a mixed solvent of toluene and hexane (toluene: hexane=1:5)was used as a developing solvent for the chromatography. The obtainedfraction was concentrated to give 0.93 g of white powder that was anobjective substance in a yield of 18%. The reaction scheme of thesynthesis method is shown in (F9-2).

The Rf value of the objective substance was 0.18, which was obtained bysilica gel thin layer chromatography (TLC) (with a developing solventcontaining ethyl acetate and hexane in a 1:10 ratio).

The compound obtained in Step 2 was examined by a nuclear magneticresonance (NMR) method. The measurement data are shown below.

¹H NMR (CDCl₃, 300 MHz): δ (ppm)=7.41-7.643 (d, J=3.4 Hz, 2H), 7.48-7.51(d, J=8.30 Hz, 2H), 7.60-8.05 (m, 20H), 8.15-8.18 (d, J=9.3 Hz, 2H),8.41 (d, J=0.98 Hz, 1H), 8.79 (dd, J=8.3 Hz, 18.6 Hz, 4H).

FIGS. 87A and 87B are ¹H NMR charts. Note that FIG. 87B is a chartshowing an enlarged part of FIG. 87A in the range of 7.00 ppm to 9.00ppm. The measurement results confirmed that9-phenyl-9H-3-[3,5-di(phenanthrene-9-yl)phenyl]carbazole (abbreviation:Pn2PPC) that was the objective substance was able to be obtained.

Note that although the example in which the carbazole compound havingchlorine as a reaction group is coupled with the phenanthrene compoundis described in this example, a carbazole compound having iodine orbromine as a reaction group may be used without limitation thereto. Acarbazole compound that can be used in Step 2 above can be representedby General Formula (12), for example. Note that in the case where thecarbazole compound represented by General Formula (12) has bromine oriodine as a reaction group, Pn2PPC can be synthesized in a mannersimilar to that in Step 2 above. In Step 1, in the case of specificallyreacting 9-phenyl-9H-carbazol-3-boronic acid with trihalogenated benzeneat 1:1, it is preferable that a halogen which reacts with boronic acidhave a higher reaction property than a halogen represented by X. Thus,in the case where X bonded to benzene at each of the 1-position and the3-position is chlorine, a halogen at the 5-position is preferablybromine or iodine. In the case where X bonded to benzene is bromine, thehalogen at the 5-position is preferably iodine.

Note that in General Formula (12), X represents chlorine, bromine, oriodine.

FIG. 88A shows an absorption spectrum of synthesized Pn2PPC in a toluenesolution of Pn2PPC, and FIG. 88B shows an emission spectrum thereof.FIG. 89A shows an absorption spectrum of a thin film of Pn2PPC, and FIG.89B shows an emission spectrum thereof. The absorption spectrum wasmeasured with an ultraviolet-visible spectrophotometer (V550, producedby JASCO Corporation). The emission spectrum was measured with afluorescence spectrophotometer (FS920, produced by Hamamatsu PhotonicsCorporation). The measurements were performed with samples prepared insuch a manner that the solution was put in a quartz cell while the thinfilm was obtained by evaporation onto a quartz substrate. FIG. 88A showthe absorption spectrum of Pn2PPC in the solution of Pn2PPC which wasobtained by subtracting the absorption spectra of the quartz cell andtoluene put therein, and FIG. 89A shows the absorption spectrum of thethin film which was obtained by subtracting the absorption spectrum ofthe quartz substrate. In FIGS. 88A and 88B and FIGS. 89A and 89B, thehorizontal axis represents wavelength (nm) and the vertical axisrepresents intensity (arbitrary unit). In the case of the toluenesolution, the absorption peak was observed at around 298 nm, and themaximum emission wavelength was 381 nm (excitation wavelength: 311 nm).In the case of the thin film, the absorption peak was observed at around303 nm, and the maximum emission wavelength was 409 nm (excitationwavelength: 304 nm).

The absorption spectrum showed that Pn2PPC described in this example isa material having weak absorption of light in the visible region. Inaddition, the emission spectrum shows that Pn2PPC exhibits blue-violetemission.

This application is based on Japanese Patent Application serial no.2010-215856 filed with Japan Patent Office on Sep. 27, 2010, the entirecontents of which are hereby incorporated by reference.

1. A phenanthrene compound represented by General Formula (I1):

wherein X represents chlorine, bromine, or iodine.
 2. A compoundrepresented by following structure


3. A light-emitting element comprising the compound according to claim2.
 4. A compound represented by following structure


5. A light-emitting element comprising the compound according to claim4.